AK+Everywhere: Rename String to DeprecatedString

We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)

28 files changed, 499 insertions, 499 deletions

diff --git a/Meta/Lagom/Fuzzers/FuzzCyrillicDecoder.cpp b/Meta/Lagom/Fuzzers/FuzzCyrillicDecoder.cpp
index e5160bde57..8bbd7cc83c 100644
--- a/Meta/Lagom/Fuzzers/FuzzCyrillicDecoder.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzCyrillicDecoder.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/String.h>
+#include <AK/DeprecatedString.h>
 #include <LibTextCodec/Decoder.h>
 #include <stddef.h>
 #include <stdint.h>
diff --git a/Meta/Lagom/Fuzzers/FuzzGIFLoader.cpp b/Meta/Lagom/Fuzzers/FuzzGIFLoader.cpp
index f066f445ae..f72354e19c 100644
--- a/Meta/Lagom/Fuzzers/FuzzGIFLoader.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzGIFLoader.cpp
@@ -5,8 +5,8 @@
  */
 
 #include <AK/Debug.h>
+#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
-#include <AK/String.h>
 #include <LibGfx/GIFLoader.h>
 #include <stddef.h>
 #include <stdint.h>
diff --git a/Meta/Lagom/Fuzzers/FuzzHebrewDecoder.cpp b/Meta/Lagom/Fuzzers/FuzzHebrewDecoder.cpp
index 162dfd6a7c..98e123df48 100644
--- a/Meta/Lagom/Fuzzers/FuzzHebrewDecoder.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzHebrewDecoder.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/String.h>
+#include <AK/DeprecatedString.h>
 #include <LibTextCodec/Decoder.h>
 #include <stddef.h>
 #include <stdint.h>
diff --git a/Meta/Lagom/Fuzzers/FuzzLatin1Decoder.cpp b/Meta/Lagom/Fuzzers/FuzzLatin1Decoder.cpp
index fefe5d341d..97733bbc7a 100644
--- a/Meta/Lagom/Fuzzers/FuzzLatin1Decoder.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzLatin1Decoder.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/String.h>
+#include <AK/DeprecatedString.h>
 #include <LibTextCodec/Decoder.h>
 #include <stddef.h>
 #include <stdint.h>
diff --git a/Meta/Lagom/Fuzzers/FuzzLatin2Decoder.cpp b/Meta/Lagom/Fuzzers/FuzzLatin2Decoder.cpp
index 5bdf6c7af0..3ff3e14ceb 100644
--- a/Meta/Lagom/Fuzzers/FuzzLatin2Decoder.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzLatin2Decoder.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/String.h>
+#include <AK/DeprecatedString.h>
 #include <LibTextCodec/Decoder.h>
 #include <stddef.h>
 #include <stdint.h>
diff --git a/Meta/Lagom/Fuzzers/FuzzQuotedPrintableParser.cpp b/Meta/Lagom/Fuzzers/FuzzQuotedPrintableParser.cpp
index ad85fcb9de..c1bf58c372 100644
--- a/Meta/Lagom/Fuzzers/FuzzQuotedPrintableParser.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzQuotedPrintableParser.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/String.h>
+#include <AK/DeprecatedString.h>
 #include <AK/StringView.h>
 #include <LibIMAP/QuotedPrintable.h>
 
diff --git a/Meta/Lagom/Fuzzers/FuzzUTF16BEDecoder.cpp b/Meta/Lagom/Fuzzers/FuzzUTF16BEDecoder.cpp
index d1e3cf43d5..f054e793d5 100644
--- a/Meta/Lagom/Fuzzers/FuzzUTF16BEDecoder.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzUTF16BEDecoder.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/String.h>
+#include <AK/DeprecatedString.h>
 #include <LibTextCodec/Decoder.h>
 #include <stddef.h>
 #include <stdint.h>
diff --git a/Meta/Lagom/Fuzzers/FuzzilliJs.cpp b/Meta/Lagom/Fuzzers/FuzzilliJs.cpp
index f55840bcac..423484ad82 100644
--- a/Meta/Lagom/Fuzzers/FuzzilliJs.cpp
+++ b/Meta/Lagom/Fuzzers/FuzzilliJs.cpp
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
-#include <AK/String.h>
 #include <AK/StringView.h>
 #include <LibJS/Forward.h>
 #include <LibJS/Interpreter.h>
diff --git a/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp b/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp
index 9eebb2f916..32fb7b5c70 100644
--- a/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp
@@ -16,12 +16,12 @@
 #include <stdio.h>
 
 struct Parameter {
-    Vector<String> attributes;
-    String type;
-    String name;
+    Vector<DeprecatedString> attributes;
+    DeprecatedString type;
+    DeprecatedString name;
 };
 
-static String pascal_case(String const& identifier)
+static DeprecatedString pascal_case(DeprecatedString const& identifier)
 {
     StringBuilder builder;
     bool was_new_word = true;
@@ -40,12 +40,12 @@ static String pascal_case(String const& identifier)
 }
 
 struct Message {
-    String name;
+    DeprecatedString name;
     bool is_synchronous { false };
     Vector<Parameter> inputs;
     Vector<Parameter> outputs;
 
-    String response_name() const
+    DeprecatedString response_name() const
     {
         StringBuilder builder;
         builder.append(pascal_case(name));
@@ -55,18 +55,18 @@ struct Message {
 };
 
 struct Endpoint {
-    Vector<String> includes;
-    String name;
+    Vector<DeprecatedString> includes;
+    DeprecatedString name;
     u32 magic;
     Vector<Message> messages;
 };
 
-static bool is_primitive_type(String const& type)
+static bool is_primitive_type(DeprecatedString const& type)
 {
     return type.is_one_of("u8", "i8", "u16", "i16", "u32", "i32", "u64", "i64", "bool", "double", "float", "int", "unsigned", "unsigned int");
 }
 
-static String message_name(String const& endpoint, String const& message, bool is_response)
+static DeprecatedString message_name(DeprecatedString const& endpoint, DeprecatedString const& message, bool is_response)
 {
     StringBuilder builder;
     builder.append("Messages::"sv);
@@ -121,7 +121,7 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
                     consume_whitespace();
                 }
             }
-            // FIXME: This is not entirely correct. Types can have spaces, for example `HashMap<int, String>`.
+            // FIXME: This is not entirely correct. Types can have spaces, for example `HashMap<int, DeprecatedString>`.
             //        Maybe we should use LibCpp::Parser for parsing types.
             parameter.type = lexer.consume_until([](char ch) { return isspace(ch); });
             VERIFY(!lexer.is_eof());
@@ -191,7 +191,7 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
     };
 
     auto parse_include = [&] {
-        String include;
+        DeprecatedString include;
         consume_whitespace();
         include = lexer.consume_while([](char ch) { return ch != '\n'; });
         consume_whitespace();
@@ -217,7 +217,7 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
         lexer.consume_specific("endpoint");
         consume_whitespace();
         endpoints.last().name = lexer.consume_while([](char ch) { return !isspace(ch); });
-        endpoints.last().magic = Traits<String>::hash(endpoints.last().name);
+        endpoints.last().magic = Traits<DeprecatedString>::hash(endpoints.last().name);
         consume_whitespace();
         assert_specific('{');
         parse_messages();
@@ -231,22 +231,22 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
     return endpoints;
 }
 
-HashMap<String, int> build_message_ids_for_endpoint(SourceGenerator generator, Endpoint const& endpoint)
+HashMap<DeprecatedString, int> build_message_ids_for_endpoint(SourceGenerator generator, Endpoint const& endpoint)
 {
-    HashMap<String, int> message_ids;
+    HashMap<DeprecatedString, int> message_ids;
 
     generator.appendln("\nenum class MessageID : i32 {");
     for (auto const& message : endpoint.messages) {
 
         message_ids.set(message.name, message_ids.size() + 1);
         generator.set("message.pascal_name", pascal_case(message.name));
-        generator.set("message.id", String::number(message_ids.size()));
+        generator.set("message.id", DeprecatedString::number(message_ids.size()));
 
         generator.appendln("    @message.pascal_name@ = @message.id@,");
         if (message.is_synchronous) {
             message_ids.set(message.response_name(), message_ids.size() + 1);
             generator.set("message.pascal_name", pascal_case(message.response_name()));
-            generator.set("message.id", String::number(message_ids.size()));
+            generator.set("message.id", DeprecatedString::number(message_ids.size()));
 
             generator.appendln("    @message.pascal_name@ = @message.id@,");
         }
@@ -255,7 +255,7 @@ HashMap<String, int> build_message_ids_for_endpoint(SourceGenerator generator, E
     return message_ids;
 }
 
-String constructor_for_message(String const& name, Vector<Parameter> const& parameters)
+DeprecatedString constructor_for_message(DeprecatedString const& name, Vector<Parameter> const& parameters)
 {
     StringBuilder builder;
     builder.append(name);
@@ -282,7 +282,7 @@ String constructor_for_message(String const& name, Vector<Parameter> const& para
     return builder.to_string();
 }
 
-void do_message(SourceGenerator message_generator, String const& name, Vector<Parameter> const& parameters, String const& response_type = {})
+void do_message(SourceGenerator message_generator, DeprecatedString const& name, Vector<Parameter> const& parameters, DeprecatedString const& response_type = {})
 {
     auto pascal_name = pascal_case(name);
     message_generator.set("message.name", name);
@@ -418,17 +418,17 @@ private:
 
 void do_message_for_proxy(SourceGenerator message_generator, Endpoint const& endpoint, Message const& message)
 {
-    auto do_implement_proxy = [&](String const& name, Vector<Parameter> const& parameters, bool is_synchronous, bool is_try) {
-        String return_type = "void";
+    auto do_implement_proxy = [&](DeprecatedString const& name, Vector<Parameter> const& parameters, bool is_synchronous, bool is_try) {
+        DeprecatedString return_type = "void";
         if (is_synchronous) {
             if (message.outputs.size() == 1)
                 return_type = message.outputs[0].type;
             else if (!message.outputs.is_empty())
                 return_type = message_name(endpoint.name, message.name, true);
         }
-        String inner_return_type = return_type;
+        DeprecatedString inner_return_type = return_type;
         if (is_try)
-            return_type = String::formatted("IPC::IPCErrorOr<{}>", return_type);
+            return_type = DeprecatedString::formatted("IPC::IPCErrorOr<{}>", return_type);
 
         message_generator.set("message.name", message.name);
         message_generator.set("message.pascal_name", pascal_case(message.name));
@@ -527,14 +527,14 @@ void do_message_for_proxy(SourceGenerator message_generator, Endpoint const& end
 void build_endpoint(SourceGenerator generator, Endpoint const& endpoint)
 {
     generator.set("endpoint.name", endpoint.name);
-    generator.set("endpoint.magic", String::number(endpoint.magic));
+    generator.set("endpoint.magic", DeprecatedString::number(endpoint.magic));
 
     generator.appendln("\nnamespace Messages::@endpoint.name@ {");
 
-    HashMap<String, int> message_ids = build_message_ids_for_endpoint(generator.fork(), endpoint);
+    HashMap<DeprecatedString, int> message_ids = build_message_ids_for_endpoint(generator.fork(), endpoint);
 
     for (auto const& message : endpoint.messages) {
-        String response_name;
+        DeprecatedString response_name;
         if (message.is_synchronous) {
             response_name = message.response_name();
             do_message(generator.fork(), response_name, message.outputs);
@@ -614,7 +614,7 @@ public:
         switch (message_id) {)~~~");
 
     for (auto const& message : endpoint.messages) {
-        auto do_decode_message = [&](String const& name) {
+        auto do_decode_message = [&](DeprecatedString const& name) {
             auto message_generator = generator.fork();
 
             message_generator.set("message.name", name);
@@ -661,13 +661,13 @@ public:
     virtual ~@endpoint.name@Stub() override { }
 
     virtual u32 magic() const override { return @endpoint.magic@; }
-    virtual String name() const override { return "@endpoint.name@"; }
+    virtual DeprecatedString name() const override { return "@endpoint.name@"; }
 
     virtual OwnPtr<IPC::MessageBuffer> handle(const IPC::Message& message) override
     {
         switch (message.message_id()) {)~~~");
     for (auto const& message : endpoint.messages) {
-        auto do_handle_message = [&](String const& name, Vector<Parameter> const& parameters, bool returns_something) {
+        auto do_handle_message = [&](DeprecatedString const& name, Vector<Parameter> const& parameters, bool returns_something) {
             auto message_generator = generator.fork();
 
             StringBuilder argument_generator;
@@ -721,8 +721,8 @@ public:
     for (auto const& message : endpoint.messages) {
         auto message_generator = generator.fork();
 
-        auto do_handle_message_decl = [&](String const& name, Vector<Parameter> const& parameters, bool is_response) {
-            String return_type = "void";
+        auto do_handle_message_decl = [&](DeprecatedString const& name, Vector<Parameter> const& parameters, bool is_response) {
+            DeprecatedString return_type = "void";
             if (message.is_synchronous && !message.outputs.is_empty() && !is_response)
                 return_type = message_name(endpoint.name, message.name, true);
             message_generator.set("message.complex_return_type", return_type);
@@ -731,7 +731,7 @@ public:
             message_generator.appendln(R"~~~(
     virtual @message.complex_return_type@ @handler_name@()~~~");
 
-            auto make_argument_type = [](String const& type) {
+            auto make_argument_type = [](DeprecatedString const& type) {
                 StringBuilder builder;
 
                 bool const_ref = !is_primitive_type(type);
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibEDID/GeneratePnpIDs.cpp b/Meta/Lagom/Tools/CodeGenerators/LibEDID/GeneratePnpIDs.cpp
index aab3df4ecd..d48b13dffe 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibEDID/GeneratePnpIDs.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibEDID/GeneratePnpIDs.cpp
@@ -23,11 +23,11 @@ struct ApprovalDate {
 };
 
 struct PnpIdData {
-    String manufacturer_name;
+    DeprecatedString manufacturer_name;
     ApprovalDate approval_date;
 };
 
-static ErrorOr<String> decode_html_entities(StringView const& str)
+static ErrorOr<DeprecatedString> decode_html_entities(StringView const& str)
 {
     static constexpr struct {
         StringView entity_name;
@@ -116,12 +116,12 @@ static ErrorOr<ApprovalDate> parse_approval_date(StringView const& str)
     return ApprovalDate { .year = year.value(), .month = month.value(), .day = day.value() };
 }
 
-static ErrorOr<HashMap<String, PnpIdData>> parse_pnp_ids_database(Core::Stream::File& pnp_ids_file)
+static ErrorOr<HashMap<DeprecatedString, PnpIdData>> parse_pnp_ids_database(Core::Stream::File& pnp_ids_file)
 {
     auto pnp_ids_file_bytes = TRY(pnp_ids_file.read_all());
     StringView pnp_ids_file_contents(pnp_ids_file_bytes);
 
-    HashMap<String, PnpIdData> pnp_id_data;
+    HashMap<DeprecatedString, PnpIdData> pnp_id_data;
 
     for (size_t row_content_offset = 0;;) {
         static auto const row_start_tag = "<tr class=\""sv;
@@ -142,7 +142,7 @@ static ErrorOr<HashMap<String, PnpIdData>> parse_pnp_ids_database(Core::Stream::
             return Error::from_string_literal("Invalid row start tag");
 
         auto row_string = pnp_ids_file_contents.substring_view(row_start_tag_end.value() + 1, row_end.value() - row_start_tag_end.value() - 1);
-        Vector<String, (size_t)PnpIdColumns::ColumnCount> columns;
+        Vector<DeprecatedString, (size_t)PnpIdColumns::ColumnCount> columns;
         for (size_t column_row_offset = 0;;) {
             static auto const column_start_tag = "<td>"sv;
             auto column_start = row_string.find(column_start_tag, column_row_offset);
@@ -181,12 +181,12 @@ static ErrorOr<HashMap<String, PnpIdData>> parse_pnp_ids_database(Core::Stream::
     return pnp_id_data;
 }
 
-static ErrorOr<void> generate_header(Core::Stream::File& file, HashMap<String, PnpIdData> const& pnp_ids)
+static ErrorOr<void> generate_header(Core::Stream::File& file, HashMap<DeprecatedString, PnpIdData> const& pnp_ids)
 {
     StringBuilder builder;
     SourceGenerator generator { builder };
 
-    generator.set("pnp_id_count", String::formatted("{}", pnp_ids.size()));
+    generator.set("pnp_id_count", DeprecatedString::formatted("{}", pnp_ids.size()));
     generator.append(R"~~~(
 #pragma once
 
@@ -215,7 +215,7 @@ namespace PnpIDs {
     return {};
 }
 
-static ErrorOr<void> generate_source(Core::Stream::File& file, HashMap<String, PnpIdData> const& pnp_ids)
+static ErrorOr<void> generate_source(Core::Stream::File& file, HashMap<DeprecatedString, PnpIdData> const& pnp_ids)
 {
     StringBuilder builder;
     SourceGenerator generator { builder };
@@ -231,9 +231,9 @@ static constexpr PnpIDData s_pnp_ids[] = {
     for (auto& pnp_id_data : pnp_ids) {
         generator.set("manufacturer_id", pnp_id_data.key);
         generator.set("manufacturer_name", pnp_id_data.value.manufacturer_name);
-        generator.set("approval_year", String::formatted("{}", pnp_id_data.value.approval_date.year));
-        generator.set("approval_month", String::formatted("{}", pnp_id_data.value.approval_date.month));
-        generator.set("approval_day", String::formatted("{}", pnp_id_data.value.approval_date.day));
+        generator.set("approval_year", DeprecatedString::formatted("{}", pnp_id_data.value.approval_date.year));
+        generator.set("approval_month", DeprecatedString::formatted("{}", pnp_id_data.value.approval_date.month));
+        generator.set("approval_day", DeprecatedString::formatted("{}", pnp_id_data.value.approval_date.day));
 
         generator.append(R"~~~(
 { "@manufacturer_id@"sv, "@manufacturer_name@"sv, { @approval_year@, @approval_month@, @approval_day@ } },
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp
index 34083106cb..df8f5257c5 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp
@@ -7,6 +7,7 @@
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
 #include <AK/AllOf.h>
 #include <AK/CharacterTypes.h>
+#include <AK/DeprecatedString.h>
 #include <AK/Find.h>
 #include <AK/Format.h>
 #include <AK/GenericLexer.h>
@@ -17,7 +18,6 @@
 #include <AK/JsonValue.h>
 #include <AK/LexicalPath.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/Traits.h>
 #include <AK/Utf8View.h>
@@ -487,7 +487,7 @@ struct AK::Formatter<Locale::HourCycle> : Formatter<FormatString> {
 };
 
 struct LocaleData {
-    HashMap<String, size_t> calendars;
+    HashMap<DeprecatedString, size_t> calendars;
 
     size_t time_zones { 0 };
     size_t time_zone_formats { 0 };
@@ -513,27 +513,27 @@ struct CLDR {
     UniqueStorage<DayPeriodList> unique_day_period_lists;
     UniqueStorage<HourCycleList> unique_hour_cycle_lists;
 
-    HashMap<String, LocaleData> locales;
+    HashMap<DeprecatedString, LocaleData> locales;
 
-    HashMap<String, size_t> hour_cycles;
-    Vector<String> hour_cycle_regions;
+    HashMap<DeprecatedString, size_t> hour_cycles;
+    Vector<DeprecatedString> hour_cycle_regions;
 
-    HashMap<String, u8> minimum_days;
-    Vector<String> minimum_days_regions;
+    HashMap<DeprecatedString, u8> minimum_days;
+    Vector<DeprecatedString> minimum_days_regions;
 
-    HashMap<String, Locale::Weekday> first_day;
-    Vector<String> first_day_regions;
+    HashMap<DeprecatedString, Locale::Weekday> first_day;
+    Vector<DeprecatedString> first_day_regions;
 
-    HashMap<String, Locale::Weekday> weekend_start;
-    Vector<String> weekend_start_regions;
+    HashMap<DeprecatedString, Locale::Weekday> weekend_start;
+    Vector<DeprecatedString> weekend_start_regions;
 
-    HashMap<String, Locale::Weekday> weekend_end;
-    Vector<String> weekend_end_regions;
+    HashMap<DeprecatedString, Locale::Weekday> weekend_end;
+    Vector<DeprecatedString> weekend_end_regions;
 
-    HashMap<String, Vector<TimeZone::TimeZone>> meta_zones;
-    Vector<String> time_zones { "UTC"sv };
+    HashMap<DeprecatedString, Vector<TimeZone::TimeZone>> meta_zones;
+    Vector<DeprecatedString> time_zones { "UTC"sv };
 
-    Vector<String> calendars;
+    Vector<DeprecatedString> calendars;
 };
 
 static Optional<Locale::DayPeriod> day_period_from_string(StringView day_period)
@@ -563,7 +563,7 @@ static Optional<Locale::DayPeriod> day_period_from_string(StringView day_period)
     return {};
 }
 
-static ErrorOr<void> parse_hour_cycles(String core_path, CLDR& cldr)
+static ErrorOr<void> parse_hour_cycles(DeprecatedString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Time_Data
     LexicalPath time_data_path(move(core_path));
@@ -607,7 +607,7 @@ static ErrorOr<void> parse_hour_cycles(String core_path, CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_week_data(String core_path, CLDR& cldr)
+static ErrorOr<void> parse_week_data(DeprecatedString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Week_Data
     LexicalPath week_data_path(move(core_path));
@@ -672,7 +672,7 @@ static ErrorOr<void> parse_week_data(String core_path, CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_meta_zones(String core_path, CLDR& cldr)
+static ErrorOr<void> parse_meta_zones(DeprecatedString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Metazones
     LexicalPath meta_zone_path(move(core_path));
@@ -714,7 +714,7 @@ static constexpr auto is_char(char ch)
 // "{hour}:{minute} {ampm}" becomes "{hour}:{minute}" (remove the space before {ampm})
 // "{ampm} {hour}" becomes "{hour}" (remove the space after {ampm})
 // "{hour}:{minute} {ampm} {timeZoneName}" becomes "{hour}:{minute} {timeZoneName}" (remove one of the spaces around {ampm})
-static String remove_period_from_pattern(String pattern)
+static DeprecatedString remove_period_from_pattern(DeprecatedString pattern)
 {
     auto is_surrounding_space = [&](auto code_point_iterator) {
         if (code_point_iterator.done())
@@ -751,15 +751,15 @@ static String remove_period_from_pattern(String pattern)
             after_removal = it;
 
         if (is_surrounding_space(before_removal) && !is_opening(after_removal)) {
-            pattern = String::formatted("{}{}",
+            pattern = DeprecatedString::formatted("{}{}",
                 pattern.substring_view(0, *index - before_removal.underlying_code_point_length_in_bytes()),
                 pattern.substring_view(*index + remove.length()));
         } else if (is_surrounding_space(after_removal) && !is_closing(before_removal)) {
-            pattern = String::formatted("{}{}",
+            pattern = DeprecatedString::formatted("{}{}",
                 pattern.substring_view(0, *index),
                 pattern.substring_view(*index + remove.length() + after_removal.underlying_code_point_length_in_bytes()));
         } else {
-            pattern = String::formatted("{}{}",
+            pattern = DeprecatedString::formatted("{}{}",
                 pattern.substring_view(0, *index),
                 pattern.substring_view(*index + remove.length()));
         }
@@ -768,7 +768,7 @@ static String remove_period_from_pattern(String pattern)
     return pattern;
 }
 
-static Optional<CalendarPattern> parse_date_time_pattern_raw(String pattern, String skeleton, CLDR& cldr)
+static Optional<CalendarPattern> parse_date_time_pattern_raw(DeprecatedString pattern, DeprecatedString skeleton, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table
     using Locale::CalendarPatternStyle;
@@ -987,7 +987,7 @@ static Optional<CalendarPattern> parse_date_time_pattern_raw(String pattern, Str
     return format;
 }
 
-static Optional<size_t> parse_date_time_pattern(String pattern, String skeleton, CLDR& cldr)
+static Optional<size_t> parse_date_time_pattern(DeprecatedString pattern, DeprecatedString skeleton, CLDR& cldr)
 {
     auto format = parse_date_time_pattern_raw(move(pattern), move(skeleton), cldr);
     if (!format.has_value())
@@ -1377,7 +1377,7 @@ static void parse_calendar_symbols(Calendar& calendar, JsonObject const& calenda
     calendar.symbols = cldr.unique_calendar_symbols_lists.ensure(move(symbols_list));
 }
 
-static ErrorOr<void> parse_calendars(String locale_calendars_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_calendars(DeprecatedString locale_calendars_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath calendars_path(move(locale_calendars_path));
     if (!calendars_path.basename().starts_with("ca-"sv))
@@ -1394,7 +1394,7 @@ static ErrorOr<void> parse_calendars(String locale_calendars_path, CLDR& cldr, L
             auto format = patterns_object.get(name);
             auto skeleton = skeletons_object.get(name);
 
-            auto format_index = parse_date_time_pattern(format.as_string(), skeleton.as_string_or(String::empty()), cldr).value();
+            auto format_index = parse_date_time_pattern(format.as_string(), skeleton.as_string_or(DeprecatedString::empty()), cldr).value();
 
             if (patterns)
                 patterns->append(cldr.unique_patterns.get(format_index));
@@ -1468,7 +1468,7 @@ static ErrorOr<void> parse_calendars(String locale_calendars_path, CLDR& cldr, L
     return {};
 }
 
-static ErrorOr<void> parse_time_zone_names(String locale_time_zone_names_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_time_zone_names(DeprecatedString locale_time_zone_names_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath time_zone_names_path(move(locale_time_zone_names_path));
     time_zone_names_path = time_zone_names_path.append("timeZoneNames.json"sv);
@@ -1577,7 +1577,7 @@ static ErrorOr<void> parse_time_zone_names(String locale_time_zone_names_path, C
     return {};
 }
 
-static ErrorOr<void> parse_day_periods(String core_path, CLDR& cldr)
+static ErrorOr<void> parse_day_periods(DeprecatedString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Day_Period_Rule_Sets
     LexicalPath day_periods_path(move(core_path));
@@ -1633,7 +1633,7 @@ static ErrorOr<void> parse_day_periods(String core_path, CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(String core_path, String dates_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedString dates_path, CLDR& cldr)
 {
     TRY(parse_hour_cycles(core_path, cldr));
     TRY(parse_week_data(core_path, cldr));
@@ -1641,7 +1641,7 @@ static ErrorOr<void> parse_all_locales(String core_path, String dates_path, CLDR
 
     auto dates_iterator = TRY(path_to_dir_iterator(move(dates_path)));
 
-    auto remove_variants_from_path = [&](String path) -> ErrorOr<String> {
+    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -1673,15 +1673,15 @@ static ErrorOr<void> parse_all_locales(String core_path, String dates_path, CLDR
     return {};
 }
 
-static String format_identifier(StringView owner, String identifier)
+static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
 {
     identifier = identifier.replace("-"sv, "_"sv, ReplaceMode::All);
     identifier = identifier.replace("/"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return String::formatted("{}_{}", owner[0], identifier);
+        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return String::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -1937,9 +1937,9 @@ struct DayPeriodData {
     cldr.unique_day_period_lists.generate(generator, cldr.unique_day_periods.type_that_fits(), "s_day_period_lists"sv);
     cldr.unique_hour_cycle_lists.generate(generator, cldr.unique_hour_cycle_lists.type_that_fits(), "s_hour_cycle_lists"sv);
 
-    auto append_calendars = [&](String name, auto const& calendars) {
+    auto append_calendars = [&](DeprecatedString name, auto const& calendars) {
         generator.set("name", name);
-        generator.set("size", String::number(calendars.size()));
+        generator.set("size", DeprecatedString::number(calendars.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@calendar_index_type@, @size@> @name@ { {)~~~");
@@ -1949,7 +1949,7 @@ static constexpr Array<@calendar_index_type@, @size@> @name@ { {)~~~");
             auto calendar = calendars.find(calendar_key)->value;
 
             generator.append(first ? " "sv : ", "sv);
-            generator.append(String::number(calendar));
+            generator.append(DeprecatedString::number(calendar));
             first = false;
         }
 
@@ -1959,7 +1959,7 @@ static constexpr Array<@calendar_index_type@, @size@> @name@ { {)~~~");
     auto append_mapping = [&](auto const& keys, auto const& map, auto type, auto name, auto mapping_getter) {
         generator.set("type", type);
         generator.set("name", name);
-        generator.set("size", String::number(keys.size()));
+        generator.set("size", DeprecatedString::number(keys.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {)~~~");
@@ -1970,7 +1970,7 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
             auto mapping = mapping_getter(value);
 
             generator.append(first ? " "sv : ", "sv);
-            generator.append(String::number(mapping));
+            generator.append(DeprecatedString::number(mapping));
             first = false;
         }
 
@@ -1992,7 +1992,7 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
     generator.append("\n");
 
     auto append_from_string = [&](StringView enum_title, StringView enum_snake, auto const& values, Vector<Alias> const& aliases = {}) {
-        HashValueMap<String> hashes;
+        HashValueMap<DeprecatedString> hashes;
         hashes.ensure_capacity(values.size());
 
         for (auto const& value : values)
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp
index 7b338d30fb..7e83227d6c 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp
@@ -7,6 +7,7 @@
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
 #include <AK/AllOf.h>
 #include <AK/CharacterTypes.h>
+#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
 #include <AK/JsonObject.h>
@@ -15,21 +16,20 @@
 #include <AK/LexicalPath.h>
 #include <AK/QuickSort.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/DirIterator.h>
 #include <LibCore/File.h>
 #include <LibCore/Stream.h>
 
-static String format_identifier(StringView owner, String identifier)
+static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
 {
     identifier = identifier.replace("-"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return String::formatted("{}_{}", owner[0], identifier);
+        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return String::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -153,9 +153,9 @@ using KeywordList = Vector<size_t>;
 using ListPatternList = Vector<size_t>;
 
 struct LocaleData {
-    String language;
-    Optional<String> territory;
-    Optional<String> variant;
+    DeprecatedString language;
+    Optional<DeprecatedString> territory;
+    Optional<DeprecatedString> variant;
     size_t display_patterns { 0 };
     size_t languages { 0 };
     size_t territories { 0 };
@@ -195,15 +195,15 @@ struct CLDR {
     UniqueStorage<ListPatternList> unique_list_pattern_lists;
     UniqueStorage<TextLayout> unique_text_layouts;
 
-    HashMap<String, LocaleData> locales;
+    HashMap<DeprecatedString, LocaleData> locales;
     Vector<Alias> locale_aliases;
 
-    Vector<String> languages;
-    Vector<String> territories;
-    Vector<String> scripts;
-    Vector<String> variants;
-    Vector<String> currencies;
-    Vector<String> date_fields;
+    Vector<DeprecatedString> languages;
+    Vector<DeprecatedString> territories;
+    Vector<DeprecatedString> scripts;
+    Vector<DeprecatedString> variants;
+    Vector<DeprecatedString> currencies;
+    Vector<DeprecatedString> date_fields;
     Vector<Alias> date_field_aliases {
         // ECMA-402 and the CLDR refer to some date fields with different names. Defining these aliases
         // means we can remain agnostic about the naming differences elsewhere.
@@ -212,17 +212,17 @@ struct CLDR {
         { "zone"sv, "timeZoneName"sv },
     };
 
-    HashMap<String, Vector<String>> keywords;
-    HashMap<String, Vector<Alias>> keyword_aliases;
-    HashMap<String, String> keyword_names;
-
-    Vector<String> list_pattern_types;
-    Vector<String> character_orders;
-    HashMap<String, size_t> language_aliases;
-    HashMap<String, size_t> territory_aliases;
-    HashMap<String, size_t> script_aliases;
-    HashMap<String, size_t> variant_aliases;
-    HashMap<String, size_t> subdivision_aliases;
+    HashMap<DeprecatedString, Vector<DeprecatedString>> keywords;
+    HashMap<DeprecatedString, Vector<Alias>> keyword_aliases;
+    HashMap<DeprecatedString, DeprecatedString> keyword_names;
+
+    Vector<DeprecatedString> list_pattern_types;
+    Vector<DeprecatedString> character_orders;
+    HashMap<DeprecatedString, size_t> language_aliases;
+    HashMap<DeprecatedString, size_t> territory_aliases;
+    HashMap<DeprecatedString, size_t> script_aliases;
+    HashMap<DeprecatedString, size_t> variant_aliases;
+    HashMap<DeprecatedString, size_t> subdivision_aliases;
     Vector<LanguageMapping> complex_mappings;
     Vector<LanguageMapping> likely_subtags;
     size_t max_variant_size { 0 };
@@ -245,7 +245,7 @@ static ErrorOr<LanguageMapping> parse_language_mapping(CLDR& cldr, StringView ke
     return LanguageMapping { move(parsed_key), move(parsed_alias) };
 }
 
-static ErrorOr<void> parse_core_aliases(String core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_core_aliases(DeprecatedString core_supplemental_path, CLDR& cldr)
 {
     LexicalPath core_aliases_path(move(core_supplemental_path));
     core_aliases_path = core_aliases_path.append("aliases.json"sv);
@@ -279,7 +279,7 @@ static ErrorOr<void> parse_core_aliases(String core_supplemental_path, CLDR& cld
     return {};
 }
 
-static ErrorOr<void> parse_likely_subtags(String core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_likely_subtags(DeprecatedString core_supplemental_path, CLDR& cldr)
 {
     LexicalPath likely_subtags_path(move(core_supplemental_path));
     likely_subtags_path = likely_subtags_path.append("likelySubtags.json"sv);
@@ -298,7 +298,7 @@ static ErrorOr<void> parse_likely_subtags(String core_supplemental_path, CLDR& c
     return {};
 }
 
-static ErrorOr<void> parse_identity(String locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_identity(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath languages_path(move(locale_path)); // Note: Every JSON file defines identity data, so we can use any of them.
     languages_path = languages_path.append("languages.json"sv);
@@ -335,7 +335,7 @@ static ErrorOr<void> parse_identity(String locale_path, CLDR& cldr, LocaleData&
     return {};
 }
 
-static ErrorOr<void> parse_locale_display_patterns(String locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_display_patterns(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath locale_display_names_path(move(locale_path));
     locale_display_names_path = locale_display_names_path.append("localeDisplayNames.json"sv);
@@ -356,7 +356,7 @@ static ErrorOr<void> parse_locale_display_patterns(String locale_path, CLDR& cld
     return {};
 }
 
-static ErrorOr<void> preprocess_languages(String locale_path, CLDR& cldr)
+static ErrorOr<void> preprocess_languages(DeprecatedString locale_path, CLDR& cldr)
 {
     LexicalPath languages_path(move(locale_path));
     languages_path = languages_path.append("languages.json"sv);
@@ -375,7 +375,7 @@ static ErrorOr<void> preprocess_languages(String locale_path, CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_unicode_extension_keywords(String bcp47_path, CLDR& cldr)
+static ErrorOr<void> parse_unicode_extension_keywords(DeprecatedString bcp47_path, CLDR& cldr)
 {
     constexpr auto desired_keywords = Array { "ca"sv, "co"sv, "hc"sv, "kf"sv, "kn"sv, "nu"sv };
     auto keywords = TRY(read_json_file(bcp47_path));
@@ -426,7 +426,7 @@ static ErrorOr<void> parse_unicode_extension_keywords(String bcp47_path, CLDR& c
     return {};
 }
 
-static Optional<String> find_keyword_alias(StringView key, StringView calendar, CLDR& cldr)
+static Optional<DeprecatedString> find_keyword_alias(StringView key, StringView calendar, CLDR& cldr)
 {
     auto it = cldr.keyword_aliases.find(key);
     if (it == cldr.keyword_aliases.end())
@@ -439,7 +439,7 @@ static Optional<String> find_keyword_alias(StringView key, StringView calendar,
     return alias->name;
 }
 
-static ErrorOr<void> parse_locale_languages(String locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_languages(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath languages_path(move(locale_path));
     languages_path = languages_path.append("languages.json"sv);
@@ -465,7 +465,7 @@ static ErrorOr<void> parse_locale_languages(String locale_path, CLDR& cldr, Loca
     return {};
 }
 
-static ErrorOr<void> parse_locale_territories(String locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_territories(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath territories_path(move(locale_path));
     territories_path = territories_path.append("territories.json"sv);
@@ -488,7 +488,7 @@ static ErrorOr<void> parse_locale_territories(String locale_path, CLDR& cldr, Lo
     return {};
 }
 
-static ErrorOr<void> parse_locale_scripts(String locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_scripts(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath scripts_path(move(locale_path));
     scripts_path = scripts_path.append("scripts.json"sv);
@@ -511,7 +511,7 @@ static ErrorOr<void> parse_locale_scripts(String locale_path, CLDR& cldr, Locale
     return {};
 }
 
-static ErrorOr<void> parse_locale_list_patterns(String misc_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_list_patterns(DeprecatedString misc_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath list_patterns_path(move(misc_path));
     list_patterns_path = list_patterns_path.append("listPatterns.json"sv);
@@ -562,7 +562,7 @@ static ErrorOr<void> parse_locale_list_patterns(String misc_path, CLDR& cldr, Lo
     return {};
 }
 
-static ErrorOr<void> parse_locale_layout(String misc_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_layout(DeprecatedString misc_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath layout_path(move(misc_path));
     layout_path = layout_path.append("layout.json"sv);
@@ -594,7 +594,7 @@ static ErrorOr<void> parse_locale_layout(String misc_path, CLDR& cldr, LocaleDat
     return {};
 }
 
-static ErrorOr<void> parse_locale_currencies(String numbers_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_currencies(DeprecatedString numbers_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath currencies_path(move(numbers_path));
     currencies_path = currencies_path.append("currencies.json"sv);
@@ -642,7 +642,7 @@ static ErrorOr<void> parse_locale_currencies(String numbers_path, CLDR& cldr, Lo
     return {};
 }
 
-static ErrorOr<void> parse_locale_calendars(String locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_calendars(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath locale_display_names_path(move(locale_path));
     locale_display_names_path = locale_display_names_path.append("localeDisplayNames.json"sv);
@@ -673,7 +673,7 @@ static ErrorOr<void> parse_locale_calendars(String locale_path, CLDR& cldr, Loca
     return {};
 }
 
-static ErrorOr<void> parse_locale_date_fields(String dates_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_date_fields(DeprecatedString dates_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath date_fields_path(move(dates_path));
     date_fields_path = date_fields_path.append("dateFields.json"sv);
@@ -714,8 +714,8 @@ static ErrorOr<void> parse_locale_date_fields(String dates_path, CLDR& cldr, Loc
             return;
 
         auto const& long_name = value.as_object().get("displayName"sv);
-        auto const& short_name = fields_object.as_object().get(String::formatted("{}-short", key)).as_object().get("displayName"sv);
-        auto const& narrow_name = fields_object.as_object().get(String::formatted("{}-narrow", key)).as_object().get("displayName"sv);
+        auto const& short_name = fields_object.as_object().get(DeprecatedString::formatted("{}-short", key)).as_object().get("displayName"sv);
+        auto const& narrow_name = fields_object.as_object().get(DeprecatedString::formatted("{}-narrow", key)).as_object().get("displayName"sv);
 
         auto index = cldr.date_fields.find_first_index(key).value();
         long_date_fields[index] = cldr.unique_strings.ensure(long_name.as_string());
@@ -729,7 +729,7 @@ static ErrorOr<void> parse_locale_date_fields(String dates_path, CLDR& cldr, Loc
     return {};
 }
 
-static ErrorOr<void> parse_number_system_keywords(String locale_numbers_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_number_system_keywords(DeprecatedString locale_numbers_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath numbers_path(move(locale_numbers_path));
     numbers_path = numbers_path.append("numbers.json"sv);
@@ -743,7 +743,7 @@ static ErrorOr<void> parse_number_system_keywords(String locale_numbers_path, CL
 
     KeywordList keywords {};
 
-    auto append_numbering_system = [&](String system_name) {
+    auto append_numbering_system = [&](DeprecatedString system_name) {
         if (auto system_alias = find_keyword_alias("nu"sv, system_name, cldr); system_alias.has_value())
             system_name = system_alias.release_value();
 
@@ -768,7 +768,7 @@ static ErrorOr<void> parse_number_system_keywords(String locale_numbers_path, CL
     return {};
 }
 
-static ErrorOr<void> parse_calendar_keywords(String locale_dates_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_calendar_keywords(DeprecatedString locale_dates_path, CLDR& cldr, LocaleData& locale)
 {
     auto calendars_iterator = TRY(path_to_dir_iterator(locale_dates_path, {}));
     KeywordList keywords {};
@@ -833,7 +833,7 @@ static void fill_in_collation_keywords(CLDR& cldr, LocaleData& locale)
     locale.collation_numeric_keywords = kn_index;
 }
 
-static ErrorOr<void> parse_default_content_locales(String core_path, CLDR& cldr)
+static ErrorOr<void> parse_default_content_locales(DeprecatedString core_path, CLDR& cldr)
 {
     LexicalPath default_content_path(move(core_path));
     default_content_path = default_content_path.append("defaultContent.json"sv);
@@ -882,7 +882,7 @@ static ErrorOr<void> define_aliases_without_scripts(CLDR& cldr)
         if ((parsed_locale.language == 0) || (parsed_locale.script == 0) || (parsed_locale.region == 0))
             return {};
 
-        auto locale_without_script = String::formatted("{}-{}",
+        auto locale_without_script = DeprecatedString::formatted("{}-{}",
             cldr.unique_strings.get(parsed_locale.language),
             cldr.unique_strings.get(parsed_locale.region));
 
@@ -907,7 +907,7 @@ static ErrorOr<void> define_aliases_without_scripts(CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(String bcp47_path, String core_path, String locale_names_path, String misc_path, String numbers_path, String dates_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(DeprecatedString bcp47_path, DeprecatedString core_path, DeprecatedString locale_names_path, DeprecatedString misc_path, DeprecatedString numbers_path, DeprecatedString dates_path, CLDR& cldr)
 {
     auto bcp47_iterator = TRY(path_to_dir_iterator(move(bcp47_path), "bcp47"sv));
     auto identity_iterator = TRY(path_to_dir_iterator(locale_names_path));
@@ -924,7 +924,7 @@ static ErrorOr<void> parse_all_locales(String bcp47_path, String core_path, Stri
     TRY(parse_core_aliases(core_supplemental_path.string(), cldr));
     TRY(parse_likely_subtags(core_supplemental_path.string(), cldr));
 
-    auto remove_variants_from_path = [&](String path) -> ErrorOr<String> {
+    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -1034,7 +1034,7 @@ namespace Locale {
 
     for (auto& keyword : cldr.keywords) {
         auto const& keyword_name = cldr.keyword_names.find(keyword.key)->value;
-        auto enum_name = String::formatted("Keyword{}", format_identifier({}, keyword_name));
+        auto enum_name = DeprecatedString::formatted("Keyword{}", format_identifier({}, keyword_name));
 
         if (auto aliases = cldr.keyword_aliases.find(keyword.key); aliases != cldr.keyword_aliases.end())
             generate_enum(generator, format_identifier, enum_name, {}, keyword.value, aliases->value);
@@ -1057,9 +1057,9 @@ static ErrorOr<void> generate_unicode_locale_implementation(Core::Stream::Buffer
     StringBuilder builder;
     SourceGenerator generator { builder };
     generator.set("string_index_type"sv, string_index_type);
-    generator.set("locales_size"sv, String::number(cldr.locales.size()));
-    generator.set("territories_size", String::number(cldr.territories.size()));
-    generator.set("variants_size", String::number(cldr.max_variant_size));
+    generator.set("locales_size"sv, DeprecatedString::number(cldr.locales.size()));
+    generator.set("territories_size", DeprecatedString::number(cldr.territories.size()));
+    generator.set("variants_size", DeprecatedString::number(cldr.max_variant_size));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -1162,7 +1162,7 @@ Span<StringView const> get_available_keyword_values(StringView key)
     cldr.unique_text_layouts.generate(generator, "TextLayout"sv, "s_text_layouts"sv, 30);
 
     auto append_index = [&](auto index) {
-        generator.append(String::formatted(", {}", index));
+        generator.append(DeprecatedString::formatted(", {}", index));
     };
 
     auto append_list_and_size = [&](auto const& list) {
@@ -1175,16 +1175,16 @@ Span<StringView const> get_available_keyword_values(StringView key)
         generator.append(", {");
         for (auto const& item : list) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(String::number(item));
+            generator.append(DeprecatedString::number(item));
             first = false;
         }
-        generator.append(String::formatted(" }}, {}", list.size()));
+        generator.append(DeprecatedString::formatted(" }}, {}", list.size()));
     };
 
     auto append_mapping = [&](auto const& keys, auto const& map, auto type, auto name, auto mapping_getter) {
         generator.set("type", type);
         generator.set("name", name);
-        generator.set("size", String::number(keys.size()));
+        generator.set("size", DeprecatedString::number(keys.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {)~~~");
@@ -1195,7 +1195,7 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
             auto mapping = mapping_getter(value);
 
             generator.append(first ? " "sv : ", "sv);
-            generator.append(String::number(mapping));
+            generator.append(DeprecatedString::number(mapping));
             first = false;
         }
 
@@ -1243,7 +1243,7 @@ struct CanonicalLanguageID {
         return language_id;
     }
 
-    bool matches_variants(Vector<String> const& other_variants) const {
+    bool matches_variants(Vector<DeprecatedString> const& other_variants) const {
         if (variants_size == 0)
             return true;
         if (other_variants.size() != variants_size)
@@ -1272,7 +1272,7 @@ struct LanguageMapping {
 )~~~");
 
     auto append_complex_mapping = [&](StringView name, auto& mappings) {
-        generator.set("size", String::number(mappings.size()));
+        generator.set("size", DeprecatedString::number(mappings.size()));
         generator.set("name"sv, name);
 
         generator.append(R"~~~(
@@ -1292,14 +1292,14 @@ static constexpr Array<LanguageMapping, @size@> s_@name@ { {
         });
 
         for (auto const& mapping : mappings) {
-            generator.set("language"sv, String::number(mapping.key.language));
+            generator.set("language"sv, DeprecatedString::number(mapping.key.language));
             generator.append("    { { @language@");
 
             append_index(mapping.key.script);
             append_index(mapping.key.region);
             append_list_and_size(mapping.key.variants);
 
-            generator.set("language"sv, String::number(mapping.alias.language));
+            generator.set("language"sv, DeprecatedString::number(mapping.alias.language));
             generator.append(" }, { @language@");
 
             append_index(mapping.alias.script);
@@ -1439,7 +1439,7 @@ Optional<StringView> get_locale_@enum_snake@_mapping(StringView locale, StringVi
     };
 
     auto append_from_string = [&](StringView enum_title, StringView enum_snake, auto const& values, Vector<Alias> const& aliases = {}) {
-        HashValueMap<String> hashes;
+        HashValueMap<DeprecatedString> hashes;
         hashes.ensure_capacity(values.size());
 
         for (auto const& value : values)
@@ -1493,8 +1493,8 @@ Optional<StringView> get_locale_@enum_snake@_mapping(StringView locale, StringVi
 
     for (auto const& keyword : cldr.keywords) {
         auto const& keyword_name = cldr.keyword_names.find(keyword.key)->value;
-        auto enum_name = String::formatted("Keyword{}", format_identifier({}, keyword_name));
-        auto enum_snake = String::formatted("keyword_{}", keyword.key);
+        auto enum_name = DeprecatedString::formatted("Keyword{}", format_identifier({}, keyword_name));
+        auto enum_snake = DeprecatedString::formatted("keyword_{}", keyword.key);
 
         if (auto aliases = cldr.keyword_aliases.find(keyword.key); aliases != cldr.keyword_aliases.end())
             append_from_string(enum_name, enum_snake, keyword.value, aliases->value);
@@ -1728,7 +1728,7 @@ Optional<LanguageID> add_likely_subtags(LanguageID const& language_id)
     return maximized;
 }
 
-Optional<String> resolve_most_likely_territory(LanguageID const& language_id)
+Optional<DeprecatedString> resolve_most_likely_territory(LanguageID const& language_id)
 {
     if (auto const* likely_subtag = resolve_likely_subtag(language_id); likely_subtag != nullptr)
         return decode_string(likely_subtag->alias.region);
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp
index 351c861bc9..9bd837d7eb 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp
@@ -8,6 +8,7 @@
 #include <AK/AllOf.h>
 #include <AK/Array.h>
 #include <AK/CharacterTypes.h>
+#include <AK/DeprecatedString.h>
 #include <AK/Find.h>
 #include <AK/Format.h>
 #include <AK/HashFunctions.h>
@@ -18,7 +19,6 @@
 #include <AK/LexicalPath.h>
 #include <AK/QuickSort.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/Traits.h>
 #include <AK/Utf8View.h>
@@ -220,7 +220,7 @@ struct AK::Traits<Unit> : public GenericTraits<Unit> {
 
 struct LocaleData {
     Vector<size_t> number_systems;
-    HashMap<String, size_t> units {};
+    HashMap<DeprecatedString, size_t> units {};
     u8 minimum_grouping_digits { 0 };
 };
 
@@ -232,14 +232,14 @@ struct CLDR {
     UniqueStorage<NumberSystem> unique_systems;
     UniqueStorage<Unit> unique_units;
 
-    HashMap<String, Array<u32, 10>> number_system_digits;
-    Vector<String> number_systems;
+    HashMap<DeprecatedString, Array<u32, 10>> number_system_digits;
+    Vector<DeprecatedString> number_systems;
 
-    HashMap<String, LocaleData> locales;
+    HashMap<DeprecatedString, LocaleData> locales;
     size_t max_identifier_count { 0 };
 };
 
-static ErrorOr<void> parse_number_system_digits(String core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_number_system_digits(DeprecatedString core_supplemental_path, CLDR& cldr)
 {
     LexicalPath number_systems_path(move(core_supplemental_path));
     number_systems_path = number_systems_path.append("numberingSystems.json"sv);
@@ -271,7 +271,7 @@ static ErrorOr<void> parse_number_system_digits(String core_supplemental_path, C
     return {};
 }
 
-static String parse_identifiers(String pattern, StringView replacement, CLDR& cldr, NumberFormat& format)
+static DeprecatedString parse_identifiers(DeprecatedString pattern, StringView replacement, CLDR& cldr, NumberFormat& format)
 {
     static constexpr Utf8View whitespace { "\u0020\u00a0\u200f"sv };
 
@@ -317,7 +317,7 @@ static String parse_identifiers(String pattern, StringView replacement, CLDR& cl
             cldr.max_identifier_count = max(cldr.max_identifier_count, format.identifier_indices.size());
         }
 
-        pattern = String::formatted("{}{{{}:{}}}{}",
+        pattern = DeprecatedString::formatted("{}{{{}:{}}}{}",
             *start_index > 0 ? pattern.substring_view(0, *start_index) : ""sv,
             replacement,
             replacement_index,
@@ -325,13 +325,13 @@ static String parse_identifiers(String pattern, StringView replacement, CLDR& cl
     }
 }
 
-static void parse_number_pattern(Vector<String> patterns, CLDR& cldr, NumberFormatType type, NumberFormat& format, NumberSystem* number_system_for_groupings = nullptr)
+static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr, NumberFormatType type, NumberFormat& format, NumberSystem* number_system_for_groupings = nullptr)
 {
     // https://unicode.org/reports/tr35/tr35-numbers.html#Number_Format_Patterns
     // https://cldr.unicode.org/translation/number-currency-formats/number-and-currency-patterns
     VERIFY((patterns.size() == 1) || (patterns.size() == 2));
 
-    auto replace_patterns = [&](String pattern) {
+    auto replace_patterns = [&](DeprecatedString pattern) {
         static HashMap<StringView, StringView> replacements = {
             { "{0}"sv, "{number}"sv },
             { "{1}"sv, "{currency}"sv },
@@ -345,7 +345,7 @@ static void parse_number_pattern(Vector<String> patterns, CLDR& cldr, NumberForm
         for (auto const& replacement : replacements)
             pattern = pattern.replace(replacement.key, replacement.value, ReplaceMode::All);
 
-        if (auto start_number_index = pattern.find_any_of("#0"sv, String::SearchDirection::Forward); start_number_index.has_value()) {
+        if (auto start_number_index = pattern.find_any_of("#0"sv, DeprecatedString::SearchDirection::Forward); start_number_index.has_value()) {
             auto end_number_index = *start_number_index + 1;
 
             for (; end_number_index < pattern.length(); ++end_number_index) {
@@ -372,7 +372,7 @@ static void parse_number_pattern(Vector<String> patterns, CLDR& cldr, NumberForm
                 }
             }
 
-            pattern = String::formatted("{}{{number}}{}",
+            pattern = DeprecatedString::formatted("{}{{number}}{}",
                 *start_number_index > 0 ? pattern.substring_view(0, *start_number_index) : ""sv,
                 pattern.substring_view(end_number_index));
 
@@ -389,19 +389,19 @@ static void parse_number_pattern(Vector<String> patterns, CLDR& cldr, NumberForm
     };
 
     auto zero_format = replace_patterns(move(patterns[0]));
-    format.positive_format_index = cldr.unique_strings.ensure(String::formatted("{{plusSign}}{}", zero_format));
+    format.positive_format_index = cldr.unique_strings.ensure(DeprecatedString::formatted("{{plusSign}}{}", zero_format));
 
     if (patterns.size() == 2) {
         auto negative_format = replace_patterns(move(patterns[1]));
         format.negative_format_index = cldr.unique_strings.ensure(move(negative_format));
     } else {
-        format.negative_format_index = cldr.unique_strings.ensure(String::formatted("{{minusSign}}{}", zero_format));
+        format.negative_format_index = cldr.unique_strings.ensure(DeprecatedString::formatted("{{minusSign}}{}", zero_format));
     }
 
     format.zero_format_index = cldr.unique_strings.ensure(move(zero_format));
 }
 
-static void parse_number_pattern(Vector<String> patterns, CLDR& cldr, NumberFormatType type, size_t& format_index, NumberSystem* number_system_for_groupings = nullptr)
+static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr, NumberFormatType type, size_t& format_index, NumberSystem* number_system_for_groupings = nullptr)
 {
     NumberFormat format {};
     parse_number_pattern(move(patterns), cldr, type, format, number_system_for_groupings);
@@ -409,7 +409,7 @@ static void parse_number_pattern(Vector<String> patterns, CLDR& cldr, NumberForm
     format_index = cldr.unique_formats.ensure(move(format));
 }
 
-static ErrorOr<void> parse_number_systems(String locale_numbers_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath numbers_path(move(locale_numbers_path));
     numbers_path = numbers_path.append("numbers.json"sv);
@@ -522,7 +522,7 @@ static ErrorOr<void> parse_number_systems(String locale_numbers_path, CLDR& cldr
 
             // The range separator does not appear in the symbols list, we have to extract it from
             // the range pattern.
-            auto misc_patterns_key = String::formatted("{}{}", misc_patterns_prefix, system);
+            auto misc_patterns_key = DeprecatedString::formatted("{}{}", misc_patterns_prefix, system);
             auto misc_patterns = locale_numbers_object.as_object().get(misc_patterns_key);
             auto range_separator = misc_patterns.as_object().get("range"sv).as_string();
 
@@ -594,7 +594,7 @@ static ErrorOr<void> parse_number_systems(String locale_numbers_path, CLDR& cldr
     return {};
 }
 
-static ErrorOr<void> parse_units(String locale_units_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_units(DeprecatedString locale_units_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath units_path(move(locale_units_path));
     units_path = units_path.append("units.json"sv);
@@ -607,7 +607,7 @@ static ErrorOr<void> parse_units(String locale_units_path, CLDR& cldr, LocaleDat
     auto const& short_object = locale_units_object.as_object().get("short"sv);
     auto const& narrow_object = locale_units_object.as_object().get("narrow"sv);
 
-    HashMap<String, Unit> units;
+    HashMap<DeprecatedString, Unit> units;
 
     auto ensure_unit = [&](auto const& unit) -> Unit& {
         return units.ensure(unit, [&]() {
@@ -697,7 +697,7 @@ static ErrorOr<void> parse_units(String locale_units_path, CLDR& cldr, LocaleDat
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(String core_path, String numbers_path, String units_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedString numbers_path, DeprecatedString units_path, CLDR& cldr)
 {
     auto numbers_iterator = TRY(path_to_dir_iterator(move(numbers_path)));
     auto units_iterator = TRY(path_to_dir_iterator(move(units_path)));
@@ -708,7 +708,7 @@ static ErrorOr<void> parse_all_locales(String core_path, String numbers_path, St
 
     TRY(parse_number_system_digits(core_supplemental_path.string(), cldr));
 
-    auto remove_variants_from_path = [&](String path) -> ErrorOr<String> {
+    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -740,7 +740,7 @@ static ErrorOr<void> parse_all_locales(String core_path, String numbers_path, St
     return {};
 }
 
-static String format_identifier(StringView, String identifier)
+static DeprecatedString format_identifier(StringView, DeprecatedString identifier)
 {
     return identifier.to_titlecase();
 }
@@ -776,7 +776,7 @@ static ErrorOr<void> generate_unicode_locale_implementation(Core::Stream::Buffer
     generator.set("number_format_index_type"sv, cldr.unique_formats.type_that_fits());
     generator.set("number_format_list_index_type"sv, cldr.unique_format_lists.type_that_fits());
     generator.set("numeric_symbol_list_index_type"sv, cldr.unique_symbols.type_that_fits());
-    generator.set("identifier_count", String::number(cldr.max_identifier_count));
+    generator.set("identifier_count", DeprecatedString::number(cldr.max_identifier_count));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -860,22 +860,22 @@ struct Unit {
     auto locales = cldr.locales.keys();
     quick_sort(locales);
 
-    generator.set("size", String::number(locales.size()));
+    generator.set("size", DeprecatedString::number(locales.size()));
     generator.append(R"~~~(
 static constexpr Array<u8, @size@> s_minimum_grouping_digits { { )~~~");
 
     bool first = true;
     for (auto const& locale : locales) {
         generator.append(first ? " "sv : ", "sv);
-        generator.append(String::number(cldr.locales.find(locale)->value.minimum_grouping_digits));
+        generator.append(DeprecatedString::number(cldr.locales.find(locale)->value.minimum_grouping_digits));
         first = false;
     }
     generator.append(" } };\n");
 
-    auto append_map = [&](String name, auto type, auto const& map) {
+    auto append_map = [&](DeprecatedString name, auto type, auto const& map) {
         generator.set("name", name);
         generator.set("type", type);
-        generator.set("size", String::number(map.size()));
+        generator.set("size", DeprecatedString::number(map.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {)~~~");
@@ -884,9 +884,9 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
         for (auto const& item : map) {
             generator.append(first ? " "sv : ", "sv);
             if constexpr (requires { item.value; })
-                generator.append(String::number(item.value));
+                generator.append(DeprecatedString::number(item.value));
             else
-                generator.append(String::number(item));
+                generator.append(DeprecatedString::number(item));
             first = false;
         }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp
index 5053862c70..40c4d843dc 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp
@@ -5,13 +5,13 @@
  */
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
+#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonParser.h>
 #include <AK/JsonValue.h>
 #include <AK/LexicalPath.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/Variant.h>
 #include <LibCore/ArgsParser.h>
@@ -19,14 +19,14 @@
 #include <LibCore/Stream.h>
 #include <LibLocale/PluralRules.h>
 
-static String format_identifier(StringView owner, String identifier)
+static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
 {
     identifier = identifier.replace("-"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return String::formatted("{}_{}", owner[0], identifier);
+        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return String::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -39,20 +39,20 @@ struct Relation {
         Inequality,
     };
 
-    String const& modulus_variable_name() const
+    DeprecatedString const& modulus_variable_name() const
     {
         VERIFY(modulus.has_value());
 
         if (!cached_modulus_variable_name.has_value())
-            cached_modulus_variable_name = String::formatted("mod_{}_{}", symbol, *modulus);
+            cached_modulus_variable_name = DeprecatedString::formatted("mod_{}_{}", symbol, *modulus);
 
         return *cached_modulus_variable_name;
     }
 
-    String const& exponential_variable_name() const
+    DeprecatedString const& exponential_variable_name() const
     {
         if (!cached_exponential_variable_name.has_value())
-            cached_exponential_variable_name = String::formatted("exp_{}", symbol);
+            cached_exponential_variable_name = DeprecatedString::formatted("exp_{}", symbol);
 
         return *cached_exponential_variable_name;
     }
@@ -65,25 +65,25 @@ struct Relation {
             else if (symbol == 'e' || symbol == 'c')
                 generator.append(exponential_variable_name());
             else
-                generator.append(String::formatted("ops.{}", Locale::PluralOperands::symbol_to_variable_name(symbol)));
+                generator.append(DeprecatedString::formatted("ops.{}", Locale::PluralOperands::symbol_to_variable_name(symbol)));
         };
 
         auto append_value = [&](u32 value) {
             append_variable_name();
             generator.append(" == "sv);
-            generator.append(String::number(value));
+            generator.append(DeprecatedString::number(value));
         };
 
         auto append_range = [&](auto const& range) {
             // This check avoids generating "0 <= unsigned_value", which is always true.
             if (range[0] != 0 || Locale::PluralOperands::symbol_requires_floating_point_modulus(symbol)) {
-                generator.append(String::formatted("{} <= ", range[0]));
+                generator.append(DeprecatedString::formatted("{} <= ", range[0]));
                 append_variable_name();
                 generator.append(" && "sv);
             }
 
             append_variable_name();
-            generator.append(String::formatted(" <= {}", range[1]));
+            generator.append(DeprecatedString::formatted(" <= {}", range[1]));
         };
 
         if (type == Type::Inequality)
@@ -106,7 +106,7 @@ struct Relation {
         generator.append(")"sv);
     }
 
-    void generate_precomputed_variables(SourceGenerator& generator, HashTable<String>& generated_variables) const
+    void generate_precomputed_variables(SourceGenerator& generator, HashTable<DeprecatedString>& generated_variables) const
     {
         // FIXME: How do we handle the exponential symbols? They seem unused by ECMA-402.
         if (symbol == 'e' || symbol == 'c') {
@@ -128,7 +128,7 @@ struct Relation {
         generated_variables.set(variable);
         generator.set("variable"sv, move(variable));
         generator.set("operand"sv, Locale::PluralOperands::symbol_to_variable_name(symbol));
-        generator.set("modulus"sv, String::number(*modulus));
+        generator.set("modulus"sv, DeprecatedString::number(*modulus));
 
         if (Locale::PluralOperands::symbol_requires_floating_point_modulus(symbol)) {
             generator.append(R"~~~(
@@ -145,8 +145,8 @@ struct Relation {
     Vector<Comparator> comparators;
 
 private:
-    mutable Optional<String> cached_modulus_variable_name;
-    mutable Optional<String> cached_exponential_variable_name;
+    mutable Optional<DeprecatedString> cached_modulus_variable_name;
+    mutable Optional<DeprecatedString> cached_exponential_variable_name;
 };
 
 struct Condition {
@@ -171,7 +171,7 @@ struct Condition {
         }
     }
 
-    void generate_precomputed_variables(SourceGenerator& generator, HashTable<String>& generated_variables) const
+    void generate_precomputed_variables(SourceGenerator& generator, HashTable<DeprecatedString>& generated_variables) const
     {
         for (auto const& conjunctions : relations) {
             for (auto const& relation : conjunctions)
@@ -183,18 +183,18 @@ struct Condition {
 };
 
 struct Range {
-    String start;
-    String end;
-    String category;
+    DeprecatedString start;
+    DeprecatedString end;
+    DeprecatedString category;
 };
 
-using Conditions = HashMap<String, Condition>;
+using Conditions = HashMap<DeprecatedString, Condition>;
 using Ranges = Vector<Range>;
 
 struct LocaleData {
-    static String generated_method_name(StringView form, StringView locale)
+    static DeprecatedString generated_method_name(StringView form, StringView locale)
     {
-        return String::formatted("{}_plurality_{}", form, format_identifier({}, locale));
+        return DeprecatedString::formatted("{}_plurality_{}", form, format_identifier({}, locale));
     }
 
     Conditions& rules_for_form(StringView form)
@@ -214,7 +214,7 @@ struct LocaleData {
 struct CLDR {
     UniqueStringStorage unique_strings;
 
-    HashMap<String, LocaleData> locales;
+    HashMap<DeprecatedString, LocaleData> locales;
 };
 
 static Relation parse_relation(StringView relation)
@@ -322,7 +322,7 @@ static void parse_condition(StringView category, StringView rule, Conditions& ru
     });
 }
 
-static ErrorOr<void> parse_plural_rules(String core_supplemental_path, StringView file_name, CLDR& cldr)
+static ErrorOr<void> parse_plural_rules(DeprecatedString core_supplemental_path, StringView file_name, CLDR& cldr)
 {
     static constexpr auto form_prefix = "plurals-type-"sv;
     static constexpr auto rule_prefix = "pluralRule-count-"sv;
@@ -357,7 +357,7 @@ static ErrorOr<void> parse_plural_rules(String core_supplemental_path, StringVie
 }
 
 // https://unicode.org/reports/tr35/tr35-numbers.html#Plural_Ranges
-static ErrorOr<void> parse_plural_ranges(String core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_plural_ranges(DeprecatedString core_supplemental_path, CLDR& cldr)
 {
     static constexpr auto start_segment = "-start-"sv;
     static constexpr auto end_segment = "-end-"sv;
@@ -393,7 +393,7 @@ static ErrorOr<void> parse_plural_ranges(String core_supplemental_path, CLDR& cl
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(String core_path, String locale_names_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedString locale_names_path, CLDR& cldr)
 {
     auto identity_iterator = TRY(path_to_dir_iterator(move(locale_names_path)));
 
@@ -401,7 +401,7 @@ static ErrorOr<void> parse_all_locales(String core_path, String locale_names_pat
     core_supplemental_path = core_supplemental_path.append("supplemental"sv);
     VERIFY(Core::File::is_directory(core_supplemental_path.string()));
 
-    auto remove_variants_from_path = [&](String path) -> ErrorOr<String> {
+    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -486,7 +486,7 @@ static PluralCategory default_range(PluralCategory, PluralCategory end)
             return;
 
         generator.set("method"sv, LocaleData::generated_method_name(form, locale));
-        HashTable<String> generated_variables;
+        HashTable<DeprecatedString> generated_variables;
 
         generator.append(R"~~~(
 static PluralCategory @method@([[maybe_unused]] PluralOperands ops)
@@ -541,7 +541,7 @@ static PluralCategory @method@(PluralCategory start, PluralCategory end)
         generator.set("type"sv, type);
         generator.set("form"sv, form);
         generator.set("default"sv, default_);
-        generator.set("size"sv, String::number(locales.size()));
+        generator.set("size"sv, DeprecatedString::number(locales.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> s_@form@_functions { {)~~~");
@@ -566,7 +566,7 @@ static constexpr Array<@type@, @size@> s_@form@_functions { {)~~~");
 
     auto append_categories = [&](auto const& name, auto const& rules) {
         generator.set("name", name);
-        generator.set("size", String::number(rules.size() + 1));
+        generator.set("size", DeprecatedString::number(rules.size() + 1));
 
         generator.append(R"~~~(
 static constexpr Array<PluralCategory, @size@> @name@ { { PluralCategory::Other)~~~");
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp
index b1bf7bdc05..8673f3fe1d 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp
@@ -5,6 +5,7 @@
  */
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
+#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
 #include <AK/JsonObject.h>
@@ -12,7 +13,6 @@
 #include <AK/JsonValue.h>
 #include <AK/LexicalPath.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/DirIterator.h>
@@ -40,9 +40,9 @@ struct RelativeTimeFormat {
             && (pattern == other.pattern);
     }
 
-    String time_unit;
-    String style;
-    String plurality;
+    DeprecatedString time_unit;
+    DeprecatedString style;
+    DeprecatedString plurality;
     size_t tense_or_number { 0 };
     size_t pattern { 0 };
 };
@@ -74,10 +74,10 @@ struct CLDR {
     UniqueStringStorage unique_strings;
     UniqueStorage<RelativeTimeFormat> unique_formats;
 
-    HashMap<String, LocaleData> locales;
+    HashMap<DeprecatedString, LocaleData> locales;
 };
 
-static ErrorOr<void> parse_date_fields(String locale_dates_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_date_fields(DeprecatedString locale_dates_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath date_fields_path(move(locale_dates_path));
     date_fields_path = date_fields_path.append("dateFields.json"sv);
@@ -136,11 +136,11 @@ static ErrorOr<void> parse_date_fields(String locale_dates_path, CLDR& cldr, Loc
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(String dates_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(DeprecatedString dates_path, CLDR& cldr)
 {
     auto dates_iterator = TRY(path_to_dir_iterator(move(dates_path)));
 
-    auto remove_variants_from_path = [&](String path) -> ErrorOr<String> {
+    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -227,9 +227,9 @@ struct RelativeTimeFormatImpl {
 
     cldr.unique_formats.generate(generator, "RelativeTimeFormatImpl"sv, "s_relative_time_formats"sv, 10);
 
-    auto append_list = [&](String name, auto const& list) {
+    auto append_list = [&](DeprecatedString name, auto const& list) {
         generator.set("name", name);
-        generator.set("size", String::number(list.size()));
+        generator.set("size", DeprecatedString::number(list.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@relative_time_format_index_type@, @size@> @name@ { {)~~~");
@@ -237,7 +237,7 @@ static constexpr Array<@relative_time_format_index_type@, @size@> @name@ { {)~~~
         bool first = true;
         for (auto index : list) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(String::number(index));
+            generator.append(DeprecatedString::number(index));
             first = false;
         }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp
index aa331c37dc..4ae9ab8f07 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp
@@ -6,10 +6,10 @@
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
 #include <AK/DateConstants.h>
+#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/Vector.h>
 #include <LibCore/ArgsParser.h>
@@ -36,7 +36,7 @@ struct TimeZoneOffset {
     i64 offset { 0 };
     Optional<DateTime> until;
 
-    Optional<String> dst_rule;
+    Optional<DeprecatedString> dst_rule;
     Optional<i32> dst_rule_index;
     i64 dst_offset { 0 };
 
@@ -56,17 +56,17 @@ struct DaylightSavingsOffset {
 struct TimeZoneData {
     UniqueStringStorage unique_strings;
 
-    HashMap<String, Vector<TimeZoneOffset>> time_zones;
-    Vector<String> time_zone_names;
+    HashMap<DeprecatedString, Vector<TimeZoneOffset>> time_zones;
+    Vector<DeprecatedString> time_zone_names;
     Vector<Alias> time_zone_aliases;
 
-    HashMap<String, Vector<DaylightSavingsOffset>> dst_offsets;
-    Vector<String> dst_offset_names;
+    HashMap<DeprecatedString, Vector<DaylightSavingsOffset>> dst_offsets;
+    Vector<DeprecatedString> dst_offset_names;
 
-    HashMap<String, TimeZone::Location> time_zone_coordinates;
+    HashMap<DeprecatedString, TimeZone::Location> time_zone_coordinates;
 
-    HashMap<String, Vector<size_t>> time_zone_regions;
-    Vector<String> time_zone_region_names;
+    HashMap<DeprecatedString, Vector<size_t>> time_zone_regions;
+    Vector<DeprecatedString> time_zone_region_names;
 };
 
 }
@@ -110,10 +110,10 @@ struct AK::Formatter<DaylightSavingsOffset> : Formatter<FormatString> {
     ErrorOr<void> format(FormatBuilder& builder, DaylightSavingsOffset const& dst_offset)
     {
         auto format_time = [&](auto year) {
-            return String::formatted("AK::Time::from_timestamp({}, 1, 1, 0, 0, 0, 0)", year);
+            return DeprecatedString::formatted("AK::Time::from_timestamp({}, 1, 1, 0, 0, 0, 0)", year);
         };
 
-        static String max_year_as_time("max_year_as_time"sv);
+        static DeprecatedString max_year_as_time("max_year_as_time"sv);
 
         return Formatter<FormatString>::format(builder,
             "{{ {}, {}, {}, {}, {} }}"sv,
@@ -422,7 +422,7 @@ static void set_dst_rule_indices(TimeZoneData& time_zone_data)
     }
 }
 
-static String format_identifier(StringView owner, String identifier)
+static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
 {
     constexpr auto gmt_time_zones = Array { "Etc/GMT"sv, "GMT"sv };
 
@@ -431,9 +431,9 @@ static String format_identifier(StringView owner, String identifier)
             auto offset = identifier.substring_view(gmt_time_zone.length());
 
             if (offset.starts_with('+'))
-                identifier = String::formatted("{}_Ahead_{}", gmt_time_zone, offset.substring_view(1));
+                identifier = DeprecatedString::formatted("{}_Ahead_{}", gmt_time_zone, offset.substring_view(1));
             else if (offset.starts_with('-'))
-                identifier = String::formatted("{}_Behind_{}", gmt_time_zone, offset.substring_view(1));
+                identifier = DeprecatedString::formatted("{}_Behind_{}", gmt_time_zone, offset.substring_view(1));
         }
     }
 
@@ -441,9 +441,9 @@ static String format_identifier(StringView owner, String identifier)
     identifier = identifier.replace("/"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return String::formatted("{}_{}", owner[0], identifier);
+        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return String::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -551,14 +551,14 @@ struct DaylightSavingsOffset {
     auto append_offsets = [&](auto const& name, auto type, auto const& offsets) {
         generator.set("name", name);
         generator.set("type", type);
-        generator.set("size", String::number(offsets.size()));
+        generator.set("size", DeprecatedString::number(offsets.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {
 )~~~");
 
         for (auto const& offset : offsets)
-            generator.append(String::formatted("    {},\n", offset));
+            generator.append(DeprecatedString::formatted("    {},\n", offset));
 
         generator.append("} };\n");
     };
@@ -580,7 +580,7 @@ static constexpr Array<@type@, @size@> @name@ { {
             auto const& time_zones = time_zone_data.time_zone_regions.find(value)->value;
 
             generator.set("name", name);
-            generator.set("size", String::number(time_zones.size()));
+            generator.set("size", DeprecatedString::number(time_zones.size()));
 
             generator.append(R"~~~(
 static constexpr Array<@string_index_type@, @size@> @name@ { {)~~~");
@@ -588,14 +588,14 @@ static constexpr Array<@string_index_type@, @size@> @name@ { {)~~~");
             bool first = true;
             for (auto const& time_zone : time_zones) {
                 generator.append(first ? " "sv : ", "sv);
-                generator.append(String::number(time_zone));
+                generator.append(DeprecatedString::number(time_zone));
                 first = false;
             }
 
             generator.append(" } };");
         });
 
-    generator.set("size", String::number(time_zone_data.time_zone_names.size()));
+    generator.set("size", DeprecatedString::number(time_zone_data.time_zone_names.size()));
     generator.append(R"~~~(
 static constexpr Array<Location, @size@> s_time_zone_locations { {
 )~~~");
@@ -603,12 +603,12 @@ static constexpr Array<Location, @size@> s_time_zone_locations { {
     for (auto const& time_zone : time_zone_data.time_zone_names) {
         auto location = time_zone_data.time_zone_coordinates.get(time_zone).value_or({});
 
-        generator.append(String::formatted("    {},\n", location));
+        generator.append(DeprecatedString::formatted("    {},\n", location));
     }
     generator.append("} };\n");
 
     auto append_string_conversions = [&](StringView enum_title, StringView enum_snake, auto const& values, Vector<Alias> const& aliases = {}) {
-        HashValueMap<String> hashes;
+        HashValueMap<DeprecatedString> hashes;
         hashes.ensure_capacity(values.size());
 
         auto hash = [](auto const& value) {
@@ -731,10 +731,10 @@ Optional<Array<NamedOffset, 2>> get_named_time_zone_offsets(TimeZone time_zone,
     auto const& time_zone_offset = find_time_zone_offset(time_zone, time);
     Array<NamedOffset, 2> named_offsets;
 
-    auto format_name = [](auto format, auto offset) -> String {
+    auto format_name = [](auto format, auto offset) -> DeprecatedString {
         if (offset == 0)
             return decode_string(format).replace("{}"sv, ""sv, ReplaceMode::FirstOnly);
-        return String::formatted(decode_string(format), decode_string(offset));
+        return DeprecatedString::formatted(decode_string(format), decode_string(offset));
     };
 
     auto set_named_offset = [&](auto& named_offset, auto dst_offset, auto in_dst, auto format, auto offset) {
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp
index 485deac41b..a8f356f686 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp
@@ -6,8 +6,8 @@
 
 #include "GeneratorUtil.h"
 #include <AK/AnyOf.h>
+#include <AK/DeprecatedString.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringUtils.h>
 #include <AK/Types.h>
 #include <LibCore/ArgsParser.h>
@@ -17,13 +17,13 @@
 
 struct Emoji {
     size_t name { 0 };
-    Optional<String> image_path;
+    Optional<DeprecatedString> image_path;
     Unicode::EmojiGroup group;
-    String subgroup;
+    DeprecatedString subgroup;
     u32 display_order { 0 };
     Vector<u32> code_points;
-    String encoded_code_points;
-    String status;
+    DeprecatedString encoded_code_points;
+    DeprecatedString status;
     size_t code_point_array_index { 0 };
 };
 
@@ -44,7 +44,7 @@ static void set_image_path_for_emoji(StringView emoji_resource_path, Emoji& emoj
         builder.appendff("U+{:X}", code_point);
     }
 
-    auto path = String::formatted("{}/{}.png", emoji_resource_path, builder.build());
+    auto path = DeprecatedString::formatted("{}/{}.png", emoji_resource_path, builder.build());
     if (Core::Stream::File::exists(path))
         emoji.image_path = move(path);
 }
@@ -57,7 +57,7 @@ static ErrorOr<void> parse_emoji_test_data(Core::Stream::BufferedFile& file, Emo
     Array<u8, 1024> buffer;
 
     Unicode::EmojiGroup group;
-    String subgroup;
+    DeprecatedString subgroup;
     u32 display_order { 0 };
 
     while (TRY(file.can_read_line())) {
@@ -178,7 +178,7 @@ static ErrorOr<void> generate_emoji_data_implementation(Core::Stream::BufferedFi
     SourceGenerator generator { builder };
 
     generator.set("string_index_type"sv, emoji_data.unique_strings.type_that_fits());
-    generator.set("emojis_size"sv, String::number(emoji_data.emojis.size()));
+    generator.set("emojis_size"sv, DeprecatedString::number(emoji_data.emojis.size()));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -198,7 +198,7 @@ namespace Unicode {
     for (auto const& emoji : emoji_data.emojis) {
         total_code_point_count += emoji.code_points.size();
     }
-    generator.set("total_code_point_count", String::number(total_code_point_count));
+    generator.set("total_code_point_count", DeprecatedString::number(total_code_point_count));
 
     generator.append(R"~~~(
 static constexpr Array<u32, @total_code_point_count@> s_emoji_code_points { {)~~~");
@@ -207,7 +207,7 @@ static constexpr Array<u32, @total_code_point_count@> s_emoji_code_points { {)~~
     for (auto const& emoji : emoji_data.emojis) {
         for (auto code_point : emoji.code_points) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(String::formatted("{:#x}", code_point));
+            generator.append(DeprecatedString::formatted("{:#x}", code_point));
             first = false;
         }
     }
@@ -245,11 +245,11 @@ struct EmojiData {
 static constexpr Array<EmojiData, @emojis_size@> s_emojis { {)~~~");
 
     for (auto const& emoji : emoji_data.emojis) {
-        generator.set("name"sv, String::number(emoji.name));
-        generator.set("group"sv, String::number(to_underlying(emoji.group)));
-        generator.set("display_order"sv, String::number(emoji.display_order));
-        generator.set("code_point_start"sv, String::number(emoji.code_point_array_index));
-        generator.set("code_point_count"sv, String::number(emoji.code_points.size()));
+        generator.set("name"sv, DeprecatedString::number(emoji.name));
+        generator.set("group"sv, DeprecatedString::number(to_underlying(emoji.group)));
+        generator.set("display_order"sv, DeprecatedString::number(emoji.display_order));
+        generator.set("code_point_start"sv, DeprecatedString::number(emoji.code_point_array_index));
+        generator.set("code_point_count"sv, DeprecatedString::number(emoji.code_points.size()));
 
         generator.append(R"~~~(
     { @name@, @group@, @display_order@, @code_point_start@, @code_point_count@ },)~~~");
@@ -312,7 +312,7 @@ static ErrorOr<void> generate_emoji_installation(Core::Stream::BufferedFile& fil
 
         generator.append("@emoji@"sv);
         generator.append(" - "sv);
-        generator.append(String::join(" "sv, emoji.code_points, "U+{:X}"sv));
+        generator.append(DeprecatedString::join(" "sv, emoji.code_points, "U+{:X}"sv));
         generator.append(" @name@ (@status@)\n"sv);
     }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp
index d9c16d5fd9..82cb41784d 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp
@@ -8,12 +8,12 @@
 #include <AK/AllOf.h>
 #include <AK/Array.h>
 #include <AK/CharacterTypes.h>
+#include <AK/DeprecatedString.h>
 #include <AK/Find.h>
 #include <AK/HashMap.h>
 #include <AK/Optional.h>
 #include <AK/QuickSort.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringUtils.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
@@ -37,21 +37,21 @@ struct SpecialCasing {
     Vector<u32> lowercase_mapping;
     Vector<u32> uppercase_mapping;
     Vector<u32> titlecase_mapping;
-    String locale;
-    String condition;
+    DeprecatedString locale;
+    DeprecatedString condition;
 };
 
 // Field descriptions: https://www.unicode.org/reports/tr44/#Character_Decomposition_Mappings
 struct CodePointDecomposition {
     // `tag` is a string since it's used for codegen as an enum value.
-    String tag { "Canonical"sv };
+    DeprecatedString tag { "Canonical"sv };
     size_t decomposition_index { 0 };
     size_t decomposition_size { 0 };
 };
 
 // PropList source: https://www.unicode.org/Public/13.0.0/ucd/PropList.txt
 // Property descriptions: https://www.unicode.org/reports/tr44/tr44-13.html#PropList.txt
-using PropList = HashMap<String, Vector<CodePointRange>>;
+using PropList = HashMap<DeprecatedString, Vector<CodePointRange>>;
 
 // Normalization source: https://www.unicode.org/Public/13.0.0/ucd/DerivedNormalizationProps.txt
 // Normalization descriptions: https://www.unicode.org/reports/tr44/#DerivedNormalizationProps.txt
@@ -67,7 +67,7 @@ struct Normalization {
     QuickCheck quick_check { QuickCheck::Yes };
 };
 
-using NormalizationProps = HashMap<String, Vector<Normalization>>;
+using NormalizationProps = HashMap<DeprecatedString, Vector<Normalization>>;
 
 struct CodePointName {
     CodePointRange code_point_range;
@@ -79,17 +79,17 @@ struct CodePointName {
 //                     https://www.unicode.org/reports/tr44/#General_Category_Values
 struct CodePointData {
     u32 code_point { 0 };
-    String name;
+    DeprecatedString name;
     Optional<size_t> abbreviation;
     u8 canonical_combining_class { 0 };
-    String bidi_class;
+    DeprecatedString bidi_class;
     Optional<CodePointDecomposition> decomposition_mapping;
     Optional<i8> numeric_value_decimal;
     Optional<i8> numeric_value_digit;
     Optional<i8> numeric_value_numeric;
     bool bidi_mirrored { false };
-    String unicode_1_name;
-    String iso_comment;
+    DeprecatedString unicode_1_name;
+    DeprecatedString iso_comment;
     Optional<u32> simple_uppercase_mapping;
     Optional<u32> simple_lowercase_mapping;
     Optional<u32> simple_titlecase_mapping;
@@ -108,7 +108,7 @@ struct UnicodeData {
 
     u32 code_points_with_decomposition_mapping { 0 };
     Vector<u32> decomposition_mappings;
-    Vector<String> compatibility_tags;
+    Vector<DeprecatedString> compatibility_tags;
 
     u32 simple_uppercase_mapping_size { 0 };
     u32 simple_lowercase_mapping_size { 0 };
@@ -117,8 +117,8 @@ struct UnicodeData {
     u32 code_points_with_special_casing { 0 };
     u32 largest_casing_transform_size { 0 };
     u32 largest_special_casing_size { 0 };
-    Vector<String> conditions;
-    Vector<String> locales;
+    Vector<DeprecatedString> conditions;
+    Vector<DeprecatedString> locales;
 
     Vector<CodePointData> code_point_data;
 
@@ -159,7 +159,7 @@ struct UnicodeData {
     PropList sentence_break_props;
 };
 
-static String sanitize_entry(String const& entry)
+static DeprecatedString sanitize_entry(DeprecatedString const& entry)
 {
     auto sanitized = entry.replace("-"sv, "_"sv, ReplaceMode::All);
     sanitized = sanitized.replace(" "sv, "_"sv, ReplaceMode::All);
@@ -243,7 +243,7 @@ static ErrorOr<void> parse_special_casing(Core::Stream::BufferedFile& file, Unic
             }
 
             if (!casing.locale.is_empty()) {
-                casing.locale = String::formatted("{:c}{}", to_ascii_uppercase(casing.locale[0]), casing.locale.substring_view(1));
+                casing.locale = DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(casing.locale[0]), casing.locale.substring_view(1));
 
                 if (!unicode_data.locales.contains_slow(casing.locale))
                     unicode_data.locales.append(casing.locale);
@@ -313,7 +313,7 @@ static ErrorOr<void> parse_prop_list(Core::Stream::BufferedFile& file, PropList&
 
 static ErrorOr<void> parse_alias_list(Core::Stream::BufferedFile& file, PropList const& prop_list, Vector<Alias>& prop_aliases)
 {
-    String current_property;
+    DeprecatedString current_property;
     Array<u8, 1024> buffer;
 
     auto append_alias = [&](auto alias, auto property) {
@@ -388,7 +388,7 @@ static ErrorOr<void> parse_name_aliases(Core::Stream::BufferedFile& file, Unicod
     return {};
 }
 
-static ErrorOr<void> parse_value_alias_list(Core::Stream::BufferedFile& file, StringView desired_category, Vector<String> const& value_list, Vector<Alias>& prop_aliases, bool primary_value_is_first = true, bool sanitize_alias = false)
+static ErrorOr<void> parse_value_alias_list(Core::Stream::BufferedFile& file, StringView desired_category, Vector<DeprecatedString> const& value_list, Vector<Alias>& prop_aliases, bool primary_value_is_first = true, bool sanitize_alias = false)
 {
     TRY(file.seek(0, Core::Stream::SeekMode::SetPosition));
     Array<u8, 1024> buffer;
@@ -553,7 +553,7 @@ static Optional<CodePointDecomposition> parse_decomposition_mapping(StringView s
     if (parts.first().starts_with('<')) {
         auto const tag = parts.take_first().trim("<>"sv);
 
-        mapping.tag = String::formatted("{:c}{}", to_ascii_uppercase(tag[0]), tag.substring_view(1));
+        mapping.tag = DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(tag[0]), tag.substring_view(1));
 
         if (!unicode_data.compatibility_tags.contains_slow(mapping.tag))
             unicode_data.compatibility_tags.append(mapping.tag);
@@ -689,14 +689,14 @@ static ErrorOr<void> generate_unicode_data_header(Core::Stream::BufferedFile& fi
 {
     StringBuilder builder;
     SourceGenerator generator { builder };
-    generator.set("casing_transform_size", String::number(unicode_data.largest_casing_transform_size));
+    generator.set("casing_transform_size", DeprecatedString::number(unicode_data.largest_casing_transform_size));
 
-    auto generate_enum = [&](StringView name, StringView default_, Vector<String> values, Vector<Alias> aliases = {}) {
+    auto generate_enum = [&](StringView name, StringView default_, Vector<DeprecatedString> values, Vector<Alias> aliases = {}) {
         quick_sort(values);
         quick_sort(aliases, [](auto& alias1, auto& alias2) { return alias1.alias < alias2.alias; });
 
         generator.set("name", name);
-        generator.set("underlying", String::formatted("{}UnderlyingType", name));
+        generator.set("underlying", DeprecatedString::formatted("{}UnderlyingType", name));
         generator.set("type", ((values.size() + !default_.is_empty()) < 256) ? "u8"sv : "u16"sv);
 
         generator.append(R"~~~(
@@ -793,8 +793,8 @@ static ErrorOr<void> generate_unicode_data_implementation(Core::Stream::Buffered
     SourceGenerator generator { builder };
 
     generator.set("string_index_type"sv, unicode_data.unique_strings.type_that_fits());
-    generator.set("largest_special_casing_size", String::number(unicode_data.largest_special_casing_size));
-    generator.set("special_casing_size", String::number(unicode_data.special_casing.size()));
+    generator.set("largest_special_casing_size", DeprecatedString::number(unicode_data.largest_special_casing_size));
+    generator.set("special_casing_size", DeprecatedString::number(unicode_data.special_casing.size()));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -802,7 +802,7 @@ static ErrorOr<void> generate_unicode_data_implementation(Core::Stream::Buffered
 #include <AK/CharacterTypes.h>
 #include <AK/Optional.h>
 #include <AK/Span.h>
-#include <AK/String.h>
+#include <AK/DeprecatedString.h>
 #include <AK/StringView.h>
 #include <LibUnicode/CharacterTypes.h>
 #include <LibUnicode/UnicodeData.h>
@@ -823,17 +823,17 @@ namespace Unicode {
         generator.append(", {");
         for (auto const& item : list) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(String::formatted(format, item));
+            generator.append(DeprecatedString::formatted(format, item));
             first = false;
         }
-        generator.append(String::formatted(" }}, {}", list.size()));
+        generator.append(DeprecatedString::formatted(" }}, {}", list.size()));
     };
 
     generator.append(R"~~~(
 static constexpr Array<SpecialCasing, @special_casing_size@> s_special_casing { {)~~~");
 
     for (auto const& casing : unicode_data.special_casing) {
-        generator.set("code_point", String::formatted("{:#x}", casing.code_point));
+        generator.set("code_point", DeprecatedString::formatted("{:#x}", casing.code_point));
         generator.append(R"~~~(
     { @code_point@)~~~");
 
@@ -910,15 +910,15 @@ struct CodePointNameComparator : public CodePointRangeComparator {
 };
 )~~~");
 
-    generator.set("decomposition_mappings_size", String::number(unicode_data.decomposition_mappings.size()));
+    generator.set("decomposition_mappings_size", DeprecatedString::number(unicode_data.decomposition_mappings.size()));
     generator.append("\nstatic constexpr Array<u32, @decomposition_mappings_size@> s_decomposition_mappings_data { ");
-    generator.append(String::join(", "sv, unicode_data.decomposition_mappings, "{:#x}"sv));
+    generator.append(DeprecatedString::join(", "sv, unicode_data.decomposition_mappings, "{:#x}"sv));
     generator.append(" };\n");
 
     auto append_code_point_mappings = [&](StringView name, StringView mapping_type, u32 size, auto mapping_getter) {
         generator.set("name", name);
         generator.set("mapping_type", mapping_type);
-        generator.set("size", String::number(size));
+        generator.set("size", DeprecatedString::number(size));
 
         generator.append(R"~~~(
 static constexpr Array<@mapping_type@, @size@> s_@name@_mappings { {
@@ -941,16 +941,16 @@ static constexpr Array<@mapping_type@, @size@> s_@name@_mappings { {
             if (mappings_in_current_row++ > 0)
                 generator.append(" ");
 
-            generator.set("code_point", String::formatted("{:#x}", data.code_point));
+            generator.set("code_point", DeprecatedString::formatted("{:#x}", data.code_point));
             generator.append("{ @code_point@");
 
             if constexpr (IsSame<decltype(mapping), Optional<u32>> || IsSame<decltype(mapping), Optional<size_t>>) {
-                generator.set("mapping", String::formatted("{:#x}", *mapping));
+                generator.set("mapping", DeprecatedString::formatted("{:#x}", *mapping));
                 generator.append(", @mapping@ },");
             } else if constexpr (IsSame<decltype(mapping), Optional<CodePointDecomposition>>) {
                 generator.set("tag", mapping->tag);
-                generator.set("start", String::number(mapping->decomposition_index));
-                generator.set("size", String::number(mapping->decomposition_size));
+                generator.set("start", DeprecatedString::number(mapping->decomposition_index));
+                generator.set("size", DeprecatedString::number(mapping->decomposition_size));
                 generator.append(", CompatibilityFormattingTag::@tag@, @start@, @size@ },");
             } else {
                 append_list_and_size(data.special_casing_indices, "&s_special_casing[{}]"sv);
@@ -983,9 +983,9 @@ static constexpr Array<@mapping_type@, @size@> s_@name@_mappings { {
             return data.decomposition_mapping;
         });
 
-    auto append_code_point_range_list = [&](String name, Vector<CodePointRange> const& ranges) {
+    auto append_code_point_range_list = [&](DeprecatedString name, Vector<CodePointRange> const& ranges) {
         generator.set("name", name);
-        generator.set("size", String::number(ranges.size()));
+        generator.set("size", DeprecatedString::number(ranges.size()));
         generator.append(R"~~~(
 static constexpr Array<CodePointRange, @size@> @name@ { {
     )~~~");
@@ -997,8 +997,8 @@ static constexpr Array<CodePointRange, @size@> @name@ { {
             if (ranges_in_current_row++ > 0)
                 generator.append(" ");
 
-            generator.set("first", String::formatted("{:#x}", range.first));
-            generator.set("last", String::formatted("{:#x}", range.last));
+            generator.set("first", DeprecatedString::formatted("{:#x}", range.first));
+            generator.set("last", DeprecatedString::formatted("{:#x}", range.last));
             generator.append("{ @first@, @last@ },");
 
             if (ranges_in_current_row == max_ranges_per_row) {
@@ -1014,7 +1014,7 @@ static constexpr Array<CodePointRange, @size@> @name@ { {
 
     auto append_prop_list = [&](StringView collection_name, StringView property_format, PropList const& property_list) {
         for (auto const& property : property_list) {
-            auto name = String::formatted(property_format, property.key);
+            auto name = DeprecatedString::formatted(property_format, property.key);
             append_code_point_range_list(move(name), property.value);
         }
 
@@ -1022,12 +1022,12 @@ static constexpr Array<CodePointRange, @size@> @name@ { {
         quick_sort(property_names);
 
         generator.set("name", collection_name);
-        generator.set("size", String::number(property_names.size()));
+        generator.set("size", DeprecatedString::number(property_names.size()));
         generator.append(R"~~~(
 static constexpr Array<Span<CodePointRange const>, @size@> @name@ { {)~~~");
 
         for (auto const& property_name : property_names) {
-            generator.set("name", String::formatted(property_format, property_name));
+            generator.set("name", DeprecatedString::formatted(property_format, property_name));
             generator.append(R"~~~(
     @name@.span(),)~~~");
         }
@@ -1052,7 +1052,7 @@ static constexpr Array<Span<CodePointRange const>, @size@> @name@ { {)~~~");
 
         generator.set("type", type);
         generator.set("name", name);
-        generator.set("size", String::number(display_names.size()));
+        generator.set("size", DeprecatedString::number(display_names.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {
@@ -1061,9 +1061,9 @@ static constexpr Array<@type@, @size@> @name@ { {
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            generator.set("first", String::formatted("{:#x}", display_name.code_point_range.first));
-            generator.set("last", String::formatted("{:#x}", display_name.code_point_range.last));
-            generator.set("name", String::number(display_name.name));
+            generator.set("first", DeprecatedString::formatted("{:#x}", display_name.code_point_range.first));
+            generator.set("last", DeprecatedString::formatted("{:#x}", display_name.code_point_range.last));
+            generator.set("name", DeprecatedString::number(display_name.name));
             generator.append("{ { @first@, @last@ }, @name@ }");
 
             if (values_in_current_row == max_values_per_row) {
@@ -1104,13 +1104,13 @@ Span<BlockName const> block_display_names()
     return display_names.span();
 }
 
-Optional<String> code_point_display_name(u32 code_point)
+Optional<DeprecatedString> code_point_display_name(u32 code_point)
 {
     if (auto const* entry = binary_search(s_code_point_display_names, code_point, nullptr, CodePointNameComparator {})) {
         auto display_name = decode_string(entry->display_name);
 
         if (display_name.ends_with("{:X}"sv))
-            return String::formatted(display_name, code_point);
+            return DeprecatedString::formatted(display_name, code_point);
 
         return display_name;
     }
@@ -1197,7 +1197,7 @@ bool code_point_has_@enum_snake@(u32 code_point, @enum_title@ @enum_snake@)
         ValueFromStringOptions options {};
 
         for (auto const& prop : prop_list) {
-            if constexpr (IsSame<RemoveCVReference<decltype(prop)>, String>) {
+            if constexpr (IsSame<RemoveCVReference<decltype(prop)>, DeprecatedString>) {
                 hashes.set(CaseInsensitiveStringViewTraits::hash(prop), prop);
                 options.sensitivity = CaseSensitivity::CaseInsensitive;
             } else {
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h
index 1c28e08bca..9a8753e980 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h
+++ b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/HashFunctions.h>
 #include <AK/HashMap.h>
@@ -15,7 +16,6 @@
 #include <AK/Optional.h>
 #include <AK/QuickSort.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
 #include <AK/Traits.h>
@@ -102,7 +102,7 @@ public:
     {
         generator.set("type"sv, type);
         generator.set("name"sv, name);
-        generator.set("size"sv, String::number(m_storage.size()));
+        generator.set("size"sv, DeprecatedString::number(m_storage.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@ + 1> @name@ { {
@@ -114,10 +114,10 @@ static constexpr Array<@type@, @size@ + 1> @name@ { {
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            if constexpr (IsSame<StorageType, String>)
-                generator.append(String::formatted("\"{}\"sv", value));
+            if constexpr (IsSame<StorageType, DeprecatedString>)
+                generator.append(DeprecatedString::formatted("\"{}\"sv", value));
             else
-                generator.append(String::formatted("{}", value));
+                generator.append(DeprecatedString::formatted("{}", value));
 
             if (values_in_current_row == max_values_per_row) {
                 values_in_current_row = 0;
@@ -139,8 +139,8 @@ static constexpr Array<@type@, @size@ + 1> @name@ { {
         for (size_t i = 0; i < m_storage.size(); ++i) {
             auto const& list = m_storage[i];
 
-            generator.set("index"sv, String::number(i));
-            generator.set("size"sv, String::number(list.size()));
+            generator.set("index"sv, DeprecatedString::number(i));
+            generator.set("size"sv, DeprecatedString::number(list.size()));
 
             generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@@index@ { {)~~~");
@@ -148,14 +148,14 @@ static constexpr Array<@type@, @size@> @name@@index@ { {)~~~");
             bool first = true;
             for (auto const& value : list) {
                 generator.append(first ? " "sv : ", "sv);
-                generator.append(String::formatted("{}", value));
+                generator.append(DeprecatedString::formatted("{}", value));
                 first = false;
             }
 
             generator.append(" } };");
         }
 
-        generator.set("size"sv, String::number(m_storage.size()));
+        generator.set("size"sv, DeprecatedString::number(m_storage.size()));
 
         generator.append(R"~~~(
 
@@ -169,7 +169,7 @@ static constexpr Array<Span<@type@ const>, @size@ + 1> @name@ { {
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            generator.set("index"sv, String::number(i));
+            generator.set("index"sv, DeprecatedString::number(i));
             generator.append("@name@@index@.span()");
 
             if (values_in_current_row == max_values_per_row) {
@@ -188,8 +188,8 @@ protected:
     HashMap<StorageType, size_t> m_storage_indices;
 };
 
-class UniqueStringStorage : public UniqueStorage<String> {
-    using Base = UniqueStorage<String>;
+class UniqueStringStorage : public UniqueStorage<DeprecatedString> {
+    using Base = UniqueStorage<DeprecatedString>;
 
 public:
     // The goal of the string table generator is to ensure the table is located within the read-only
@@ -205,7 +205,7 @@ public:
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            generator.append(String::formatted("{:#x}", value));
+            generator.append(DeprecatedString::formatted("{:#x}", value));
 
             if (values_in_current_row == max_values_per_row) {
                 values_in_current_row = 0;
@@ -225,7 +225,7 @@ public:
             next_index += string.length() + 2;
         }
 
-        generator.set("size", String::number(next_index));
+        generator.set("size", DeprecatedString::number(next_index));
         generator.append(R"~~~(
 static constexpr Array<u8, @size@> s_encoded_strings { {
     )~~~");
@@ -243,7 +243,7 @@ static constexpr Array<u8, @size@> s_encoded_strings { {
 } };
 )~~~");
 
-        generator.set("size", String::number(string_indices.size()));
+        generator.set("size", DeprecatedString::number(string_indices.size()));
         generator.append(R"~~~(
 static constexpr Array<u32, @size@> s_encoded_string_indices { {
     )~~~");
@@ -277,8 +277,8 @@ static constexpr StringView decode_string(size_t index)
 };
 
 struct Alias {
-    String name;
-    String alias;
+    DeprecatedString name;
+    DeprecatedString alias;
 };
 
 struct CanonicalLanguageID {
@@ -342,7 +342,7 @@ inline ErrorOr<JsonValue> read_json_file(StringView path)
     return JsonValue::from_string(buffer);
 }
 
-inline ErrorOr<Core::DirIterator> path_to_dir_iterator(String path, StringView subpath = "main"sv)
+inline ErrorOr<Core::DirIterator> path_to_dir_iterator(DeprecatedString path, StringView subpath = "main"sv)
 {
     LexicalPath lexical_path(move(path));
     if (!subpath.is_empty())
@@ -359,7 +359,7 @@ inline ErrorOr<Core::DirIterator> path_to_dir_iterator(String path, StringView s
     return iterator;
 }
 
-inline ErrorOr<String> next_path_from_dir_iterator(Core::DirIterator& iterator)
+inline ErrorOr<DeprecatedString> next_path_from_dir_iterator(Core::DirIterator& iterator)
 {
     auto next_path = iterator.next_full_path();
     if (iterator.has_error()) {
@@ -416,11 +416,11 @@ void generate_value_from_string(SourceGenerator& generator, StringView method_na
 {
     ensure_from_string_types_are_generated(generator);
 
-    generator.set("method_name", String::formatted(method_name_format, value_name));
+    generator.set("method_name", DeprecatedString::formatted(method_name_format, value_name));
     generator.set("value_type", value_type);
     generator.set("value_name", value_name);
     generator.set("return_type", options.return_type.has_value() ? *options.return_type : value_type);
-    generator.set("size", String::number(hashes.size()));
+    generator.set("size", DeprecatedString::number(hashes.size()));
 
     generator.append(R"~~~(
 Optional<@return_type@> @method_name@(StringView key)
@@ -439,11 +439,11 @@ Optional<@return_type@> @method_name@(StringView key)
             generator.append(" ");
 
         if constexpr (IsIntegral<ValueType>)
-            generator.set("value"sv, String::number(hashes.get(hash_key).value()));
+            generator.set("value"sv, DeprecatedString::number(hashes.get(hash_key).value()));
         else
-            generator.set("value"sv, String::formatted("{}::{}", value_type, hashes.get(hash_key).value()));
+            generator.set("value"sv, DeprecatedString::formatted("{}::{}", value_type, hashes.get(hash_key).value()));
 
-        generator.set("hash"sv, String::number(hash_key));
+        generator.set("hash"sv, DeprecatedString::number(hash_key));
         generator.append("{ @hash@U, @value@ },"sv);
 
         if (values_in_current_row == max_values_per_row) {
@@ -452,7 +452,7 @@ Optional<@return_type@> @method_name@(StringView key)
         }
     }
 
-    generator.set("return_statement", String::formatted(options.return_format, "value->value"sv));
+    generator.set("return_statement", DeprecatedString::formatted(options.return_format, "value->value"sv));
     generator.append(R"~~~(
     } };
 )~~~");
@@ -476,9 +476,9 @@ Optional<@return_type@> @method_name@(StringView key)
 }
 
 template<typename IdentifierFormatter>
-void generate_value_to_string(SourceGenerator& generator, StringView method_name_format, StringView value_type, StringView value_name, IdentifierFormatter&& format_identifier, Span<String const> values)
+void generate_value_to_string(SourceGenerator& generator, StringView method_name_format, StringView value_type, StringView value_name, IdentifierFormatter&& format_identifier, Span<DeprecatedString const> values)
 {
-    generator.set("method_name", String::formatted(method_name_format, value_name));
+    generator.set("method_name", DeprecatedString::formatted(method_name_format, value_name));
     generator.set("value_type", value_type);
     generator.set("value_name", value_name);
 
@@ -506,7 +506,7 @@ StringView @method_name@(@value_type@ @value_name@)
 }
 
 template<typename IdentifierFormatter>
-void generate_enum(SourceGenerator& generator, IdentifierFormatter&& format_identifier, StringView name, StringView default_, Vector<String>& values, Vector<Alias> aliases = {})
+void generate_enum(SourceGenerator& generator, IdentifierFormatter&& format_identifier, StringView name, StringView default_, Vector<DeprecatedString>& values, Vector<Alias> aliases = {})
 {
     quick_sort(values, [](auto const& value1, auto const& value2) { return value1.to_lowercase() < value2.to_lowercase(); });
     quick_sort(aliases, [](auto const& alias1, auto const& alias2) { return alias1.alias.to_lowercase() < alias2.alias.to_lowercase(); });
@@ -545,20 +545,20 @@ template<typename LocalesType, typename IdentifierFormatter, typename ListFormat
 void generate_mapping(SourceGenerator& generator, LocalesType const& locales, StringView type, StringView name, StringView format, IdentifierFormatter&& format_identifier, ListFormatter&& format_list)
 {
     auto format_mapping_name = [&](StringView format, StringView name) {
-        String mapping_name;
+        DeprecatedString mapping_name;
 
         if constexpr (IsNullPointer<IdentifierFormatter>)
             mapping_name = name.replace("-"sv, "_"sv, ReplaceMode::All);
         else
             mapping_name = format_identifier(type, name);
 
-        return String::formatted(format, mapping_name.to_lowercase());
+        return DeprecatedString::formatted(format, mapping_name.to_lowercase());
     };
 
-    Vector<String> mapping_names;
+    Vector<DeprecatedString> mapping_names;
 
     for (auto const& locale : locales) {
-        String mapping_name;
+        DeprecatedString mapping_name;
 
         if constexpr (requires { locale.key; }) {
             mapping_name = format_mapping_name(format, locale.key);
@@ -575,7 +575,7 @@ void generate_mapping(SourceGenerator& generator, LocalesType const& locales, St
 
     generator.set("type", type);
     generator.set("name", name);
-    generator.set("size", String::number(locales.size()));
+    generator.set("size", DeprecatedString::number(locales.size()));
     generator.append(R"~~~(
 static constexpr Array<Span<@type@ const>, @size@> @name@ { {
     )~~~");
@@ -620,9 +620,9 @@ Span<StringView const> @name@()
         first = false;
 
         if (auto it = aliases.find_if([&](auto const& alias) { return alias.alias == value; }); it != aliases.end())
-            generator.append(String::formatted("\"{}\"sv", it->name));
+            generator.append(DeprecatedString::formatted("\"{}\"sv", it->name));
         else
-            generator.append(String::formatted("\"{}\"sv", value));
+            generator.append(DeprecatedString::formatted("\"{}\"sv", value));
     }
 
     generator.append(R"~~~( };
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
index a316d696a9..5ceab3934d 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
@@ -69,7 +69,7 @@ static StringView sequence_storage_type_to_cpp_storage_type_name(SequenceStorage
 
 CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface);
 
-static String union_type_to_variant(UnionType const& union_type, Interface const& interface)
+static DeprecatedString union_type_to_variant(UnionType const& union_type, Interface const& interface)
 {
     StringBuilder builder;
     builder.append("Variant<"sv);
@@ -95,10 +95,10 @@ static String union_type_to_variant(UnionType const& union_type, Interface const
 CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
 {
     if (is_platform_object(type))
-        return { .name = String::formatted("JS::Handle<{}>", type.name()), .sequence_storage_type = SequenceStorageType::MarkedVector };
+        return { .name = DeprecatedString::formatted("JS::Handle<{}>", type.name()), .sequence_storage_type = SequenceStorageType::MarkedVector };
 
     if (type.is_string())
-        return { .name = "String", .sequence_storage_type = SequenceStorageType::Vector };
+        return { .name = "DeprecatedString", .sequence_storage_type = SequenceStorageType::Vector };
 
     if (type.name() == "double" && !type.is_nullable())
         return { .name = "double", .sequence_storage_type = SequenceStorageType::Vector };
@@ -139,7 +139,7 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
         if (sequence_cpp_type.sequence_storage_type == SequenceStorageType::MarkedVector)
             return { .name = storage_type_name, .sequence_storage_type = SequenceStorageType::Vector };
 
-        return { .name = String::formatted("{}<{}>", storage_type_name, sequence_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
+        return { .name = DeprecatedString::formatted("{}<{}>", storage_type_name, sequence_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
     }
 
     if (type.name() == "record") {
@@ -149,7 +149,7 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
         auto record_key_cpp_type = idl_type_name_to_cpp_type(record_key_type, interface);
         auto record_value_cpp_type = idl_type_name_to_cpp_type(record_value_type, interface);
 
-        return { .name = String::formatted("OrderedHashMap<{}, {}>", record_key_cpp_type.name, record_value_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
+        return { .name = DeprecatedString::formatted("OrderedHashMap<{}, {}>", record_key_cpp_type.name, record_value_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
     }
 
     if (is<UnionType>(type)) {
@@ -168,7 +168,7 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
     TODO();
 }
 
-static String make_input_acceptable_cpp(String const& input)
+static DeprecatedString make_input_acceptable_cpp(DeprecatedString const& input)
 {
     if (input.is_one_of("class", "template", "for", "default", "char", "namespace", "delete", "inline")) {
         StringBuilder builder;
@@ -206,7 +206,7 @@ static void generate_include_for(auto& generator, auto& path)
     }
 
     LexicalPath include_path { path_string };
-    forked_generator.set("include.path", String::formatted("{}/{}.h", include_path.dirname(), include_path.title()));
+    forked_generator.set("include.path", DeprecatedString::formatted("{}/{}.h", include_path.dirname(), include_path.title()));
     forked_generator.append(R"~~~(
 #include <@include.path@>
 )~~~");
@@ -215,7 +215,7 @@ static void generate_include_for(auto& generator, auto& path)
 static void emit_includes_for_all_imports(auto& interface, auto& generator, bool is_iterator = false)
 {
     Queue<RemoveCVReference<decltype(interface)> const*> interfaces;
-    HashTable<String> paths_imported;
+    HashTable<DeprecatedString> paths_imported;
 
     interfaces.enqueue(&interface);
 
@@ -236,15 +236,15 @@ static void emit_includes_for_all_imports(auto& interface, auto& generator, bool
         generate_include_for(generator, interface->module_own_path);
 
         if (is_iterator) {
-            auto iterator_name = String::formatted("{}Iterator", interface->name);
-            auto iterator_path = String::formatted("{}Iterator", interface->fully_qualified_name.replace("::"sv, "/"sv, ReplaceMode::All));
+            auto iterator_name = DeprecatedString::formatted("{}Iterator", interface->name);
+            auto iterator_path = DeprecatedString::formatted("{}Iterator", interface->fully_qualified_name.replace("::"sv, "/"sv, ReplaceMode::All));
             generate_include_for_iterator(generator, iterator_path, iterator_name);
         }
     }
 }
 
 template<typename ParameterType>
-static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter, String const& js_name, String const& js_suffix, String const& cpp_name, IDL::Interface const& interface, bool legacy_null_to_empty_string = false, bool optional = false, Optional<String> optional_default_value = {}, bool variadic = false, size_t recursion_depth = 0)
+static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter, DeprecatedString const& js_name, DeprecatedString const& js_suffix, DeprecatedString const& cpp_name, IDL::Interface const& interface, bool legacy_null_to_empty_string = false, bool optional = false, Optional<DeprecatedString> optional_default_value = {}, bool variadic = false, size_t recursion_depth = 0)
 {
     auto scoped_generator = generator.fork();
     auto acceptable_cpp_name = make_input_acceptable_cpp(cpp_name);
@@ -261,7 +261,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     if (parameter.type->is_string()) {
         if (variadic) {
             scoped_generator.append(R"~~~(
-    Vector<String> @cpp_name@;
+    Vector<DeprecatedString> @cpp_name@;
     @cpp_name@.ensure_capacity(vm.argument_count() - @js_suffix@);
 
     for (size_t i = @js_suffix@; i < vm.argument_count(); ++i) {
@@ -272,26 +272,26 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         } else if (!optional) {
             if (!parameter.type->is_nullable()) {
                 scoped_generator.append(R"~~~(
-    String @cpp_name@;
+    DeprecatedString @cpp_name@;
     if (@js_name@@js_suffix@.is_null() && @legacy_null_to_empty_string@) {
-        @cpp_name@ = String::empty();
+        @cpp_name@ = DeprecatedString::empty();
     } else {
         @cpp_name@ = TRY(@js_name@@js_suffix@.to_string(vm));
     }
 )~~~");
             } else {
                 scoped_generator.append(R"~~~(
-    String @cpp_name@;
+    DeprecatedString @cpp_name@;
     if (!@js_name@@js_suffix@.is_nullish())
         @cpp_name@ = TRY(@js_name@@js_suffix@.to_string(vm));
 )~~~");
             }
         } else {
             scoped_generator.append(R"~~~(
-    String @cpp_name@;
+    DeprecatedString @cpp_name@;
     if (!@js_name@@js_suffix@.is_undefined()) {
         if (@js_name@@js_suffix@.is_null() && @legacy_null_to_empty_string@)
-            @cpp_name@ = String::empty();
+            @cpp_name@ = DeprecatedString::empty();
         else
             @cpp_name@ = TRY(@js_name@@js_suffix@.to_string(vm));
     })~~~");
@@ -573,7 +573,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         auto default_value_cpp_name = enumeration.translated_cpp_names.get(enum_member_name);
         VERIFY(default_value_cpp_name.has_value());
         enum_generator.set("enum.default.cpp_value", *default_value_cpp_name);
-        enum_generator.set("js_name.as_string", String::formatted("{}{}_string", enum_generator.get("js_name"sv), enum_generator.get("js_suffix"sv)));
+        enum_generator.set("js_name.as_string", DeprecatedString::formatted("{}{}_string", enum_generator.get("js_name"sv), enum_generator.get("js_suffix"sv)));
         enum_generator.append(R"~~~(
     @parameter.type.name@ @cpp_name@ { @parameter.type.name@::@enum.default.cpp_value@ };
 )~~~");
@@ -634,8 +634,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
             for (auto& member : current_dictionary->members) {
                 dictionary_generator.set("member_key", member.name);
                 auto member_js_name = make_input_acceptable_cpp(member.name.to_snakecase());
-                auto member_value_name = String::formatted("{}_value", member_js_name);
-                auto member_property_value_name = String::formatted("{}_property_value", member_js_name);
+                auto member_value_name = DeprecatedString::formatted("{}_value", member_js_name);
+                auto member_property_value_name = DeprecatedString::formatted("{}_property_value", member_js_name);
                 dictionary_generator.set("member_name", member_js_name);
                 dictionary_generator.set("member_value_name", member_value_name);
                 dictionary_generator.set("member_property_value_name", member_property_value_name);
@@ -705,7 +705,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         auto sequence_generator = scoped_generator.fork();
         auto& parameterized_type = verify_cast<IDL::ParameterizedType>(*parameter.type);
-        sequence_generator.set("recursion_depth", String::number(recursion_depth));
+        sequence_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
 
         // An ECMAScript value V is converted to an IDL sequence<T> value as follows:
         // 1. If Type(V) is not Object, throw a TypeError.
@@ -757,7 +757,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotIterable, @js_name@@js_suffix@.to_string_without_side_effects());
 )~~~");
 
-        parameterized_type.generate_sequence_from_iterable(sequence_generator, String::formatted("{}{}", acceptable_cpp_name, optional ? "_non_optional" : ""), String::formatted("{}{}", js_name, js_suffix), String::formatted("iterator_method{}", recursion_depth), interface, recursion_depth + 1);
+        parameterized_type.generate_sequence_from_iterable(sequence_generator, DeprecatedString::formatted("{}{}", acceptable_cpp_name, optional ? "_non_optional" : ""), DeprecatedString::formatted("{}{}", js_name, js_suffix), DeprecatedString::formatted("iterator_method{}", recursion_depth), interface, recursion_depth + 1);
 
         if (optional) {
             sequence_generator.append(R"~~~(
@@ -770,7 +770,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         auto record_generator = scoped_generator.fork();
         auto& parameterized_type = verify_cast<IDL::ParameterizedType>(*parameter.type);
-        record_generator.set("recursion_depth", String::number(recursion_depth));
+        record_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
 
         // A record can only have two types: key type and value type.
         VERIFY(parameterized_type.parameters().size() == 2);
@@ -820,7 +820,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
 
         IDL::Parameter key_parameter { .type = parameterized_type.parameters()[0], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
-        generate_to_cpp(record_generator, key_parameter, "key", String::number(recursion_depth), String::formatted("typed_key{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
+        generate_to_cpp(record_generator, key_parameter, "key", DeprecatedString::number(recursion_depth), DeprecatedString::formatted("typed_key{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
 
         record_generator.append(R"~~~(
         auto value@recursion_depth@ = TRY(@js_name@@js_suffix@_object.get(property_key@recursion_depth@));
@@ -828,7 +828,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         // FIXME: Record value types should be TypeWithExtendedAttributes, which would allow us to get [LegacyNullToEmptyString] here.
         IDL::Parameter value_parameter { .type = parameterized_type.parameters()[1], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
-        generate_to_cpp(record_generator, value_parameter, "value", String::number(recursion_depth), String::formatted("typed_value{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
+        generate_to_cpp(record_generator, value_parameter, "value", DeprecatedString::number(recursion_depth), DeprecatedString::formatted("typed_value{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
 
         record_generator.append(R"~~~(
         @cpp_name@.set(typed_key@recursion_depth@, typed_value@recursion_depth@);
@@ -841,7 +841,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         auto& union_type = verify_cast<IDL::UnionType>(*parameter.type);
         union_generator.set("union_type", union_type_to_variant(union_type, interface));
-        union_generator.set("recursion_depth", String::number(recursion_depth));
+        union_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
 
         // NOTE: This is handled out here as we need the dictionary conversion code for the {} optional default value.
         // 3. Let types be the flattened member types of the union type.
@@ -891,7 +891,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         to_variant_captures.append("&vm, &realm"sv);
 
         if (dictionary_type)
-            to_variant_captures.append(String::formatted(", &{}{}_to_dictionary", js_name, js_suffix));
+            to_variant_captures.append(DeprecatedString::formatted(", &{}{}_to_dictionary", js_name, js_suffix));
 
         union_generator.set("to_variant_captures", to_variant_captures.to_string());
 
@@ -1028,7 +1028,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         if (method) {
 )~~~");
 
-            sequence_type->generate_sequence_from_iterable(union_generator, acceptable_cpp_name, String::formatted("{}{}", js_name, js_suffix), "method", interface, recursion_depth + 1);
+            sequence_type->generate_sequence_from_iterable(union_generator, acceptable_cpp_name, DeprecatedString::formatted("{}{}", js_name, js_suffix), "method", interface, recursion_depth + 1);
 
             union_generator.append(R"~~~(
 
@@ -1113,8 +1113,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
             // NOTE: generate_to_cpp doesn't use the parameter name.
             // NOTE: generate_to_cpp will use to_{u32,etc.} which uses to_number internally and will thus use TRY, but it cannot throw as we know we are dealing with a number.
-            IDL::Parameter parameter { .type = *numeric_type, .name = String::empty(), .optional_default_value = {}, .extended_attributes = {} };
-            generate_to_cpp(union_generator, parameter, js_name, js_suffix, String::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
+            IDL::Parameter parameter { .type = *numeric_type, .name = DeprecatedString::empty(), .optional_default_value = {}, .extended_attributes = {} };
+            generate_to_cpp(union_generator, parameter, js_name, js_suffix, DeprecatedString::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
 
             union_generator.append(R"~~~(
             return @js_name@@js_suffix@_number;
@@ -1178,8 +1178,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
             // NOTE: generate_to_cpp doesn't use the parameter name.
             // NOTE: generate_to_cpp will use to_{u32,etc.} which uses to_number internally and will thus use TRY, but it cannot throw as we know we are dealing with a number.
-            IDL::Parameter parameter { .type = *numeric_type, .name = String::empty(), .optional_default_value = {}, .extended_attributes = {} };
-            generate_to_cpp(union_numeric_type_generator, parameter, "x", String::empty(), "x_number", interface, false, false, {}, false, recursion_depth + 1);
+            IDL::Parameter parameter { .type = *numeric_type, .name = DeprecatedString::empty(), .optional_default_value = {}, .extended_attributes = {} };
+            generate_to_cpp(union_numeric_type_generator, parameter, "x", DeprecatedString::empty(), "x_number", interface, false, false, {}, false, recursion_depth + 1);
 
             union_numeric_type_generator.append(R"~~~(
         return x_number;
@@ -1189,8 +1189,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
             // NOTE: generate_to_cpp doesn't use the parameter name.
             // NOTE: generate_to_cpp will use to_{u32,etc.} which uses to_number internally and will thus use TRY, but it cannot throw as we know we are dealing with a number.
-            IDL::Parameter parameter { .type = *numeric_type, .name = String::empty(), .optional_default_value = {}, .extended_attributes = {} };
-            generate_to_cpp(union_generator, parameter, js_name, js_suffix, String::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
+            IDL::Parameter parameter { .type = *numeric_type, .name = DeprecatedString::empty(), .optional_default_value = {}, .extended_attributes = {} };
+            generate_to_cpp(union_generator, parameter, js_name, js_suffix, DeprecatedString::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
 
             union_generator.append(R"~~~(
         return @js_name@@js_suffix@_number;
@@ -1233,7 +1233,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
                 } else {
                     if (optional_default_value == "\"\"") {
                         union_generator.append(R"~~~(
-    @union_type@ @cpp_name@ = @js_name@@js_suffix@.is_undefined() ? String::empty() : TRY(@js_name@@js_suffix@_to_variant(@js_name@@js_suffix@));
+    @union_type@ @cpp_name@ = @js_name@@js_suffix@.is_undefined() ? DeprecatedString::empty() : TRY(@js_name@@js_suffix@_to_variant(@js_name@@js_suffix@));
 )~~~");
                     } else if (optional_default_value == "{}") {
                         VERIFY(dictionary_type);
@@ -1266,21 +1266,21 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     }
 }
 
-static void generate_argument_count_check(SourceGenerator& generator, String const& function_name, size_t argument_count)
+static void generate_argument_count_check(SourceGenerator& generator, DeprecatedString const& function_name, size_t argument_count)
 {
     if (argument_count == 0)
         return;
 
     auto argument_count_check_generator = generator.fork();
     argument_count_check_generator.set("function.name", function_name);
-    argument_count_check_generator.set("function.nargs", String::number(argument_count));
+    argument_count_check_generator.set("function.nargs", DeprecatedString::number(argument_count));
 
     if (argument_count == 1) {
         argument_count_check_generator.set(".bad_arg_count", "JS::ErrorType::BadArgCountOne");
         argument_count_check_generator.set(".arg_count_suffix", "");
     } else {
         argument_count_check_generator.set(".bad_arg_count", "JS::ErrorType::BadArgCountMany");
-        argument_count_check_generator.set(".arg_count_suffix", String::formatted(", \"{}\"", argument_count));
+        argument_count_check_generator.set(".arg_count_suffix", DeprecatedString::formatted(", \"{}\"", argument_count));
     }
 
     argument_count_check_generator.append(R"~~~(
@@ -1293,20 +1293,20 @@ static void generate_arguments(SourceGenerator& generator, Vector<IDL::Parameter
 {
     auto arguments_generator = generator.fork();
 
-    Vector<String> parameter_names;
+    Vector<DeprecatedString> parameter_names;
     size_t argument_index = 0;
     for (auto& parameter : parameters) {
         parameter_names.append(make_input_acceptable_cpp(parameter.name.to_snakecase()));
 
         if (!parameter.variadic) {
-            arguments_generator.set("argument.index", String::number(argument_index));
+            arguments_generator.set("argument.index", DeprecatedString::number(argument_index));
             arguments_generator.append(R"~~~(
     auto arg@argument.index@ = vm.argument(@argument.index@);
 )~~~");
         }
 
         bool legacy_null_to_empty_string = parameter.extended_attributes.contains("LegacyNullToEmptyString");
-        generate_to_cpp(generator, parameter, "arg", String::number(argument_index), parameter.name.to_snakecase(), interface, legacy_null_to_empty_string, parameter.optional, parameter.optional_default_value, parameter.variadic, 0);
+        generate_to_cpp(generator, parameter, "arg", DeprecatedString::number(argument_index), parameter.name.to_snakecase(), interface, legacy_null_to_empty_string, parameter.optional, parameter.optional_default_value, parameter.variadic, 0);
         ++argument_index;
     }
 
@@ -1314,13 +1314,13 @@ static void generate_arguments(SourceGenerator& generator, Vector<IDL::Parameter
 }
 
 // https://webidl.spec.whatwg.org/#create-sequence-from-iterable
-void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& generator, String const& cpp_name, String const& iterable_cpp_name, String const& iterator_method_cpp_name, IDL::Interface const& interface, size_t recursion_depth) const
+void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& generator, DeprecatedString const& cpp_name, DeprecatedString const& iterable_cpp_name, DeprecatedString const& iterator_method_cpp_name, IDL::Interface const& interface, size_t recursion_depth) const
 {
     auto sequence_generator = generator.fork();
     sequence_generator.set("cpp_name", cpp_name);
     sequence_generator.set("iterable_cpp_name", iterable_cpp_name);
     sequence_generator.set("iterator_method_cpp_name", iterator_method_cpp_name);
-    sequence_generator.set("recursion_depth", String::number(recursion_depth));
+    sequence_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
     auto sequence_cpp_type = idl_type_name_to_cpp_type(parameters().first(), interface);
     sequence_generator.set("sequence.type", sequence_cpp_type.name);
     sequence_generator.set("sequence.storage_type", sequence_storage_type_to_cpp_storage_type_name(sequence_cpp_type.sequence_storage_type));
@@ -1360,7 +1360,7 @@ void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& ge
 
     // FIXME: Sequences types should be TypeWithExtendedAttributes, which would allow us to get [LegacyNullToEmptyString] here.
     IDL::Parameter parameter { .type = parameters().first(), .name = iterable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
-    generate_to_cpp(sequence_generator, parameter, "next_item", String::number(recursion_depth), String::formatted("sequence_item{}", recursion_depth), interface, false, false, {}, false, recursion_depth);
+    generate_to_cpp(sequence_generator, parameter, "next_item", DeprecatedString::number(recursion_depth), DeprecatedString::formatted("sequence_item{}", recursion_depth), interface, false, false, {}, false, recursion_depth);
 
     sequence_generator.append(R"~~~(
         @cpp_name@.append(sequence_item@recursion_depth@);
@@ -1373,13 +1373,13 @@ enum class WrappingReference {
     Yes,
 };
 
-static void generate_wrap_statement(SourceGenerator& generator, String const& value, IDL::Type const& type, IDL::Interface const& interface, StringView result_expression, WrappingReference wrapping_reference = WrappingReference::No, size_t recursion_depth = 0)
+static void generate_wrap_statement(SourceGenerator& generator, DeprecatedString const& value, IDL::Type const& type, IDL::Interface const& interface, StringView result_expression, WrappingReference wrapping_reference = WrappingReference::No, size_t recursion_depth = 0)
 {
     auto scoped_generator = generator.fork();
     scoped_generator.set("value", value);
     scoped_generator.set("type", type.name());
     scoped_generator.set("result_expression", result_expression);
-    scoped_generator.set("recursion_depth", String::number(recursion_depth));
+    scoped_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
 
     if (type.name() == "undefined") {
         scoped_generator.append(R"~~~(
@@ -1443,7 +1443,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
             auto* wrapped_element@recursion_depth@ = &(*element@recursion_depth@);
 )~~~");
         } else {
-            generate_wrap_statement(scoped_generator, String::formatted("element{}", recursion_depth), sequence_generic_type.parameters().first(), interface, String::formatted("auto wrapped_element{} =", recursion_depth), WrappingReference::Yes, recursion_depth + 1);
+            generate_wrap_statement(scoped_generator, DeprecatedString::formatted("element{}", recursion_depth), sequence_generic_type.parameters().first(), interface, DeprecatedString::formatted("auto wrapped_element{} =", recursion_depth), WrappingReference::Yes, recursion_depth + 1);
         }
 
         scoped_generator.append(R"~~~(
@@ -1498,7 +1498,7 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
 )~~~");
 
             // NOTE: While we are using const&, the underlying type for wrappable types in unions is (Nonnull)RefPtr, which are not references.
-            generate_wrap_statement(union_generator, String::formatted("visited_union_value{}", recursion_depth), current_union_type, interface, "return"sv, WrappingReference::No, recursion_depth + 1);
+            generate_wrap_statement(union_generator, DeprecatedString::formatted("visited_union_value{}", recursion_depth), current_union_type, interface, "return"sv, WrappingReference::No, recursion_depth + 1);
 
             // End of current visit lambda.
             // The last lambda cannot have a trailing comma on the closing brace, unless the type is nullable, where an extra lambda will be generated for the Empty case.
@@ -1561,14 +1561,14 @@ static void generate_wrap_statement(SourceGenerator& generator, String const& va
         while (true) {
             for (auto& member : current_dictionary->members) {
                 dictionary_generator.set("member_key", member.name);
-                auto member_key_js_name = String::formatted("{}{}", make_input_acceptable_cpp(member.name.to_snakecase()), recursion_depth);
+                auto member_key_js_name = DeprecatedString::formatted("{}{}", make_input_acceptable_cpp(member.name.to_snakecase()), recursion_depth);
                 dictionary_generator.set("member_name", member_key_js_name);
-                auto member_value_js_name = String::formatted("{}_value", member_key_js_name);
+                auto member_value_js_name = DeprecatedString::formatted("{}_value", member_key_js_name);
                 dictionary_generator.set("member_value", member_value_js_name);
 
-                auto wrapped_value_name = String::formatted("auto wrapped_{}", member_value_js_name);
+                auto wrapped_value_name = DeprecatedString::formatted("auto wrapped_{}", member_value_js_name);
                 dictionary_generator.set("wrapped_value_name", wrapped_value_name);
-                generate_wrap_statement(dictionary_generator, String::formatted("{}.{}", value, member.name), member.type, interface, wrapped_value_name, WrappingReference::No, recursion_depth + 1);
+                generate_wrap_statement(dictionary_generator, DeprecatedString::formatted("{}.{}", value, member.name), member.type, interface, wrapped_value_name, WrappingReference::No, recursion_depth + 1);
 
                 dictionary_generator.append(R"~~~(
     MUST(dictionary_object@recursion_depth@->create_data_property("@member_key@", @wrapped_value_name@));
@@ -1617,24 +1617,24 @@ static void generate_return_statement(SourceGenerator& generator, IDL::Type cons
     return generate_wrap_statement(generator, "retval", return_type, interface, "return"sv);
 }
 
-static void generate_variable_statement(SourceGenerator& generator, String const& variable_name, IDL::Type const& value_type, String const& value_name, IDL::Interface const& interface)
+static void generate_variable_statement(SourceGenerator& generator, DeprecatedString const& variable_name, IDL::Type const& value_type, DeprecatedString const& value_name, IDL::Interface const& interface)
 {
     auto variable_generator = generator.fork();
     variable_generator.set("variable_name", variable_name);
     variable_generator.append(R"~~~(
     JS::Value @variable_name@;
 )~~~");
-    return generate_wrap_statement(generator, value_name, value_type, interface, String::formatted("{} = ", variable_name));
+    return generate_wrap_statement(generator, value_name, value_type, interface, DeprecatedString::formatted("{} = ", variable_name));
 }
 
-static void generate_function(SourceGenerator& generator, IDL::Function const& function, StaticFunction is_static_function, String const& class_name, String const& interface_fully_qualified_name, IDL::Interface const& interface)
+static void generate_function(SourceGenerator& generator, IDL::Function const& function, StaticFunction is_static_function, DeprecatedString const& class_name, DeprecatedString const& interface_fully_qualified_name, IDL::Interface const& interface)
 {
     auto function_generator = generator.fork();
     function_generator.set("class_name", class_name);
     function_generator.set("interface_fully_qualified_name", interface_fully_qualified_name);
     function_generator.set("function.name", function.name);
     function_generator.set("function.name:snakecase", make_input_acceptable_cpp(function.name.to_snakecase()));
-    function_generator.set("overload_suffix", function.is_overloaded ? String::number(function.overload_index) : String::empty());
+    function_generator.set("overload_suffix", function.is_overloaded ? DeprecatedString::number(function.overload_index) : DeprecatedString::empty());
 
     if (function.extended_attributes.contains("ImplementedAs")) {
         auto implemented_as = function.extended_attributes.get("ImplementedAs").value();
@@ -1672,7 +1672,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@@overload_suffi
         if (arguments_builder.is_empty())
             function_generator.set(".arguments", "vm");
         else
-            function_generator.set(".arguments", String::formatted("vm, {}", arguments_builder.string_view()));
+            function_generator.set(".arguments", DeprecatedString::formatted("vm, {}", arguments_builder.string_view()));
 
         function_generator.append(R"~~~(
     [[maybe_unused]] auto retval = TRY(throw_dom_exception_if_needed(vm, [&] { return @interface_fully_qualified_name@::@function.cpp_name@(@.arguments@); }));
@@ -1813,7 +1813,7 @@ static EffectiveOverloadSet compute_the_effective_overload_set(auto const& overl
     return EffectiveOverloadSet { move(overloads) };
 }
 
-static String generate_constructor_for_idl_type(Type const& type)
+static DeprecatedString generate_constructor_for_idl_type(Type const& type)
 {
     auto append_type_list = [](auto& builder, auto const& type_list) {
         bool first = true;
@@ -1830,7 +1830,7 @@ static String generate_constructor_for_idl_type(Type const& type)
 
     switch (type.kind()) {
     case Type::Kind::Plain:
-        return String::formatted("make_ref_counted<IDL::Type>(\"{}\", {})", type.name(), type.is_nullable());
+        return DeprecatedString::formatted("make_ref_counted<IDL::Type>(\"{}\", {})", type.name(), type.is_nullable());
     case Type::Kind::Parameterized: {
         auto const& parameterized_type = type.as_parameterized();
         StringBuilder builder;
@@ -1852,7 +1852,7 @@ static String generate_constructor_for_idl_type(Type const& type)
     VERIFY_NOT_REACHED();
 }
 
-static void generate_overload_arbiter(SourceGenerator& generator, auto const& overload_set, String const& class_name)
+static void generate_overload_arbiter(SourceGenerator& generator, auto const& overload_set, DeprecatedString const& class_name)
 {
     auto function_generator = generator.fork();
     function_generator.set("class_name", class_name);
@@ -1869,7 +1869,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
     auto maximum_argument_count = 0u;
     for (auto const& overload : overloads_set)
         maximum_argument_count = max(maximum_argument_count, overload.types.size());
-    function_generator.set("max_argument_count", String::number(maximum_argument_count));
+    function_generator.set("max_argument_count", DeprecatedString::number(maximum_argument_count));
     function_generator.appendln("    switch (min(@max_argument_count@, vm.argument_count())) {");
 
     // Generate the effective overload set for each argument count.
@@ -1888,8 +1888,8 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
         if (effective_overload_count == 0)
             continue;
 
-        function_generator.set("current_argument_count", String::number(argument_count));
-        function_generator.set("overload_count", String::number(effective_overload_count));
+        function_generator.set("current_argument_count", DeprecatedString::number(argument_count));
+        function_generator.set("overload_count", DeprecatedString::number(effective_overload_count));
         function_generator.appendln(R"~~~(
     case @current_argument_count@: {
         Vector<IDL::EffectiveOverloadSet::Item> overloads;
@@ -1930,7 +1930,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
             types_builder.append("}"sv);
             optionality_builder.append("}"sv);
 
-            function_generator.set("overload.callable_id", String::number(overload.callable_id));
+            function_generator.set("overload.callable_id", DeprecatedString::number(overload.callable_id));
             function_generator.set("overload.types", types_builder.to_string());
             function_generator.set("overload.optionality_values", optionality_builder.to_string());
 
@@ -1955,7 +1955,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
 )~~~");
 
     for (auto i = 0u; i < overload_set.value.size(); ++i) {
-        function_generator.set("overload_id", String::number(i));
+        function_generator.set("overload_id", DeprecatedString::number(i));
         function_generator.append(R"~~~(
     case @overload_id@:
         return @function.name:snakecase@@overload_id@(vm);
@@ -2009,7 +2009,7 @@ private:
 )~~~");
         if (overload_set.value.size() > 1) {
             for (auto i = 0u; i < overload_set.value.size(); ++i) {
-                function_generator.set("overload_suffix", String::number(i));
+                function_generator.set("overload_suffix", DeprecatedString::number(i));
                 function_generator.append(R"~~~(
     JS_DECLARE_NATIVE_FUNCTION(@function.name:snakecase@@overload_suffix@);
 )~~~");
@@ -2143,7 +2143,7 @@ JS::ThrowCompletionOr<JS::Object*> @constructor_class@::construct(FunctionObject
         // Single constructor
 
         auto& constructor = interface.constructors[0];
-        generator.set("constructor.length", String::number(constructor.shortest_length()));
+        generator.set("constructor.length", DeprecatedString::number(constructor.shortest_length()));
 
         generator.append(R"~~~(
     auto& vm = this->vm();
@@ -2191,7 +2191,7 @@ void @constructor_class@::initialize(JS::Realm& realm)
         auto constant_generator = generator.fork();
         constant_generator.set("constant.name", constant.name);
 
-        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, String::formatted("auto constant_{}_value =", constant.name));
+        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, DeprecatedString::formatted("auto constant_{}_value =", constant.name));
 
         constant_generator.append(R"~~~(
     define_direct_property("@constant.name@", constant_@constant.name@_value, JS::Attribute::Enumerable);
@@ -2203,7 +2203,7 @@ void @constructor_class@::initialize(JS::Realm& realm)
         auto function_generator = generator.fork();
         function_generator.set("function.name", overload_set.key);
         function_generator.set("function.name:snakecase", make_input_acceptable_cpp(overload_set.key.to_snakecase()));
-        function_generator.set("function.length", String::number(get_shortest_function_length(overload_set.value)));
+        function_generator.set("function.length", DeprecatedString::number(get_shortest_function_length(overload_set.value)));
 
         function_generator.append(R"~~~(
     define_native_function(realm, "@function.name@", @function.name:snakecase@, @function.length@, default_attributes);
@@ -2264,7 +2264,7 @@ private:
         )~~~");
         if (overload_set.value.size() > 1) {
             for (auto i = 0u; i < overload_set.value.size(); ++i) {
-                function_generator.set("overload_suffix", String::number(i));
+                function_generator.set("overload_suffix", DeprecatedString::number(i));
                 function_generator.append(R"~~~(
     JS_DECLARE_NATIVE_FUNCTION(@function.name:snakecase@@overload_suffix@);
 )~~~");
@@ -2326,7 +2326,7 @@ enum class @enum.type.name@ {
 
         enum_generator.append(R"~~~(
 };
-inline String idl_enum_to_string(@enum.type.name@ value) {
+inline DeprecatedString idl_enum_to_string(@enum.type.name@ value) {
     switch(value) {
 )~~~");
         for (auto& entry : it.value.translated_cpp_names) {
@@ -2364,7 +2364,7 @@ void generate_prototype_implementation(IDL::Interface const& interface)
     generator.set("fully_qualified_name", interface.fully_qualified_name);
 
     if (interface.pair_iterator_types.has_value()) {
-        generator.set("iterator_name", String::formatted("{}Iterator", interface.name));
+        generator.set("iterator_name", DeprecatedString::formatted("{}Iterator", interface.name));
     }
 
     generator.append(R"~~~(
@@ -2500,7 +2500,7 @@ void @prototype_class@::initialize(JS::Realm& realm)
         auto constant_generator = generator.fork();
         constant_generator.set("constant.name", constant.name);
 
-        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, String::formatted("auto constant_{}_value =", constant.name));
+        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, DeprecatedString::formatted("auto constant_{}_value =", constant.name));
 
         constant_generator.append(R"~~~(
     define_direct_property("@constant.name@", constant_@constant.name@_value, JS::Attribute::Enumerable);
@@ -2512,7 +2512,7 @@ void @prototype_class@::initialize(JS::Realm& realm)
         auto function_generator = generator.fork();
         function_generator.set("function.name", overload_set.key);
         function_generator.set("function.name:snakecase", make_input_acceptable_cpp(overload_set.key.to_snakecase()));
-        function_generator.set("function.length", String::number(get_shortest_function_length(overload_set.value)));
+        function_generator.set("function.length", DeprecatedString::number(get_shortest_function_length(overload_set.value)));
 
         // FIXME: What if only some of the overloads are Unscopable?
         if (any_of(overload_set.value, [](auto const& function) { return function.extended_attributes.contains("Unscopable"); })) {
@@ -2686,7 +2686,7 @@ JS_DEFINE_NATIVE_FUNCTION(@prototype_class@::@attribute.setter_callback@)
     if (!cpp_value)
         impl->remove_attribute(HTML::AttributeNames::@attribute.reflect_name@);
     else
-        MUST(impl->set_attribute(HTML::AttributeNames::@attribute.reflect_name@, String::empty()));
+        MUST(impl->set_attribute(HTML::AttributeNames::@attribute.reflect_name@, DeprecatedString::empty()));
 )~~~");
                 }
             } else {
@@ -2801,7 +2801,7 @@ void generate_iterator_prototype_header(IDL::Interface const& interface)
     StringBuilder builder;
     SourceGenerator generator { builder };
 
-    generator.set("prototype_class", String::formatted("{}IteratorPrototype", interface.name));
+    generator.set("prototype_class", DeprecatedString::formatted("{}IteratorPrototype", interface.name));
 
     generator.append(R"~~~(
 #pragma once
@@ -2833,10 +2833,10 @@ void generate_iterator_prototype_implementation(IDL::Interface const& interface)
     StringBuilder builder;
     SourceGenerator generator { builder };
 
-    generator.set("name", String::formatted("{}Iterator", interface.name));
-    generator.set("prototype_class", String::formatted("{}IteratorPrototype", interface.name));
-    generator.set("fully_qualified_name", String::formatted("{}Iterator", interface.fully_qualified_name));
-    generator.set("possible_include_path", String::formatted("{}Iterator", interface.name.replace("::"sv, "/"sv, ReplaceMode::All)));
+    generator.set("name", DeprecatedString::formatted("{}Iterator", interface.name));
+    generator.set("prototype_class", DeprecatedString::formatted("{}IteratorPrototype", interface.name));
+    generator.set("fully_qualified_name", DeprecatedString::formatted("{}Iterator", interface.fully_qualified_name));
+    generator.set("possible_include_path", DeprecatedString::formatted("{}Iterator", interface.name.replace("::"sv, "/"sv, ReplaceMode::All)));
 
     generator.append(R"~~~(
 #include <AK/Function.h>
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp
index cc25e51e3f..acfbfe9c4b 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp
@@ -58,8 +58,8 @@ enum class PropertyID {
     Custom,
 )~~~");
 
-    Vector<String> shorthand_property_ids;
-    Vector<String> longhand_property_ids;
+    Vector<DeprecatedString> shorthand_property_ids;
+    Vector<DeprecatedString> longhand_property_ids;
 
     properties.for_each_member([&](auto& name, auto& value) {
         VERIFY(value.is_object());
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp
index 5285b7ba8f..8976edacf3 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp
@@ -39,7 +39,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return 0;
 }
 
-static String title_casify_transform_function(StringView input)
+static DeprecatedString title_casify_transform_function(StringView input)
 {
     // Transform function names look like `fooBar`, so we just have to make the first character uppercase.
     StringBuilder builder;
@@ -189,7 +189,7 @@ TransformFunctionMetadata transform_function_metadata(TransformFunction transfor
             member_generator.append(first ? " "sv : ", "sv);
             first = false;
 
-            member_generator.append(String::formatted("{{ TransformFunctionParameterType::{}, {}}}", parameter_type, value.as_object().get("required"sv).to_string()));
+            member_generator.append(DeprecatedString::formatted("{{ TransformFunctionParameterType::{}, {}}}", parameter_type, value.as_object().get("required"sv).to_string()));
         });
 
         member_generator.append(R"~~~( }
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
index b831b2a458..7d23b67f1b 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
@@ -5,9 +5,9 @@
  */
 
 #include <AK/Debug.h>
+#include <AK/DeprecatedString.h>
 #include <AK/LexicalPath.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/Stream.h>
@@ -16,14 +16,14 @@
 #include <LibMain/Main.h>
 
 static ErrorOr<void> add_to_interface_sets(IDL::Interface&, Vector<IDL::Interface&>& window_exposed, Vector<IDL::Interface&>& dedicated_worker_exposed, Vector<IDL::Interface&>& shared_worker_exposed);
-static String s_error_string;
+static DeprecatedString s_error_string;
 
 static ErrorOr<void> generate_exposed_interface_header(StringView class_name, StringView output_path)
 {
     StringBuilder builder;
     SourceGenerator generator(builder);
 
-    generator.set("global_object_snake_name", String(class_name).to_snakecase());
+    generator.set("global_object_snake_name", DeprecatedString(class_name).to_snakecase());
     generator.append(R"~~~(
 #pragma once
 
@@ -37,7 +37,7 @@ void add_@global_object_snake_name@_exposed_interfaces(JS::Object&, JS::Realm&);
 
 )~~~");
 
-    auto generated_header_path = LexicalPath(output_path).append(String::formatted("{}ExposedInterfaces.h", class_name)).string();
+    auto generated_header_path = LexicalPath(output_path).append(DeprecatedString::formatted("{}ExposedInterfaces.h", class_name)).string();
     auto generated_header_file = TRY(Core::Stream::File::open(generated_header_path, Core::Stream::OpenMode::Write));
     TRY(generated_header_file->write(generator.as_string_view().bytes()));
 
@@ -50,7 +50,7 @@ static ErrorOr<void> generate_exposed_interface_implementation(StringView class_
     SourceGenerator generator(builder);
 
     generator.set("global_object_name", class_name);
-    generator.set("global_object_snake_name", String(class_name).to_snakecase());
+    generator.set("global_object_snake_name", DeprecatedString(class_name).to_snakecase());
 
     generator.append(R"~~~(
 #include <LibJS/Heap/DeferGC.h>
@@ -123,7 +123,7 @@ void add_@global_object_snake_name@_exposed_interfaces(JS::Object& global, JS::R
 }
 }
 )~~~");
-    auto generated_implementation_path = LexicalPath(output_path).append(String::formatted("{}ExposedInterfaces.cpp", class_name)).string();
+    auto generated_implementation_path = LexicalPath(output_path).append(DeprecatedString::formatted("{}ExposedInterfaces.cpp", class_name)).string();
     auto generated_implementation_file = TRY(Core::Stream::File::open(generated_implementation_path, Core::Stream::OpenMode::Write));
     TRY(generated_implementation_file->write(generator.as_string_view().bytes()));
 
@@ -136,7 +136,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     StringView output_path;
     StringView base_path;
-    Vector<String> paths;
+    Vector<DeprecatedString> paths;
 
     args_parser.add_option(output_path, "Path to output generated files into", "output-path", 'o', "output-path");
     args_parser.add_option(base_path, "Path to root of IDL file tree", "base-path", 'b', "base-path");
@@ -149,16 +149,16 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     const LexicalPath lexical_base(base_path);
 
     // Read in all IDL files, we must own the storage for all of these for the lifetime of the program
-    Vector<String> file_contents;
-    for (String const& path : paths) {
+    Vector<DeprecatedString> file_contents;
+    for (DeprecatedString const& path : paths) {
         auto file_or_error = Core::Stream::File::open(path, Core::Stream::OpenMode::Read);
         if (file_or_error.is_error()) {
-            s_error_string = String::formatted("Unable to open file {}", path);
+            s_error_string = DeprecatedString::formatted("Unable to open file {}", path);
             return Error::from_string_view(s_error_string);
         }
         auto file = file_or_error.release_value();
         auto string = MUST(file->read_all());
-        file_contents.append(String(ReadonlyBytes(string)));
+        file_contents.append(DeprecatedString(ReadonlyBytes(string)));
     }
     VERIFY(paths.size() == file_contents.size());
 
@@ -220,7 +220,7 @@ static ErrorOr<ExposedTo> parse_exposure_set(IDL::Interface& interface)
 
     auto maybe_exposed = interface.extended_attributes.get("Exposed");
     if (!maybe_exposed.has_value()) {
-        s_error_string = String::formatted("Interface {} is missing extended attribute Exposed", interface.name);
+        s_error_string = DeprecatedString::formatted("Interface {} is missing extended attribute Exposed", interface.name);
         return Error::from_string_view(s_error_string);
     }
     auto exposed = maybe_exposed.value().trim_whitespace();
@@ -250,18 +250,18 @@ static ErrorOr<ExposedTo> parse_exposure_set(IDL::Interface& interface)
             } else if (candidate == "AudioWorklet"sv) {
                 whom |= ExposedTo::AudioWorklet;
             } else {
-                s_error_string = String::formatted("Unknown Exposed attribute candidate {} in {} in {}", candidate, exposed, interface.name);
+                s_error_string = DeprecatedString::formatted("Unknown Exposed attribute candidate {} in {} in {}", candidate, exposed, interface.name);
                 return Error::from_string_view(s_error_string);
             }
         }
         if (whom == ExposedTo::Nobody) {
-            s_error_string = String::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
+            s_error_string = DeprecatedString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
             return Error::from_string_view(s_error_string);
         }
         return whom;
     }
 
-    s_error_string = String::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
+    s_error_string = DeprecatedString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
     return Error::from_string_view(s_error_string);
 }
 
@@ -275,7 +275,7 @@ static IDL::Interface& add_synthetic_interface(IDL::Interface& reference_interfa
 
     auto new_interface = make<IDL::Interface>();
     new_interface->name = name;
-    new_interface->constructor_class = String::formatted("{}Constructor", new_interface->name);
+    new_interface->constructor_class = DeprecatedString::formatted("{}Constructor", new_interface->name);
     new_interface->prototype_class = reference_interface.prototype_class;
     new_interface->parent_name = "[Synthetic Interface]";
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h
index c1e6489f7b..e86d7c9451 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h
@@ -7,13 +7,13 @@
 
 #pragma once
 
+#include <AK/DeprecatedString.h>
 #include <AK/JsonObject.h>
-#include <AK/String.h>
 #include <AK/Vector.h>
 #include <LibCore/Stream.h>
 #include <ctype.h>
 
-String title_casify(String const& dashy_name)
+DeprecatedString title_casify(DeprecatedString const& dashy_name)
 {
     auto parts = dashy_name.split('-');
     StringBuilder builder;
@@ -28,7 +28,7 @@ String title_casify(String const& dashy_name)
     return builder.to_string();
 }
 
-String camel_casify(StringView dashy_name)
+DeprecatedString camel_casify(StringView dashy_name)
 {
     auto parts = dashy_name.split_view('-');
     StringBuilder builder;
@@ -49,7 +49,7 @@ String camel_casify(StringView dashy_name)
     return builder.to_string();
 }
 
-String snake_casify(String const& dashy_name)
+DeprecatedString snake_casify(DeprecatedString const& dashy_name)
 {
     return dashy_name.replace("-"sv, "_"sv, ReplaceMode::All);
 }
diff --git a/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp b/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp
index e1c00c8e42..aff038ba59 100644
--- a/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp
@@ -4,11 +4,11 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/DeprecatedString.h>
 #include <AK/GenericLexer.h>
 #include <AK/HashTable.h>
 #include <AK/OwnPtr.h>
 #include <AK/SourceGenerator.h>
-#include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/Types.h>
 #include <LibCore/ArgsParser.h>
@@ -22,8 +22,8 @@ struct Range {
 };
 
 struct StateTransition {
-    Optional<String> new_state;
-    Optional<String> action;
+    Optional<DeprecatedString> new_state;
+    Optional<DeprecatedString> action;
 };
 
 struct MatchedAction {
@@ -32,18 +32,18 @@ struct MatchedAction {
 };
 
 struct State {
-    String name;
+    DeprecatedString name;
     Vector<MatchedAction> actions;
-    Optional<String> entry_action;
-    Optional<String> exit_action;
+    Optional<DeprecatedString> entry_action;
+    Optional<DeprecatedString> exit_action;
 };
 
 struct StateMachine {
-    String name;
-    String initial_state;
+    DeprecatedString name;
+    DeprecatedString initial_state;
     Vector<State> states;
     Optional<State> anywhere;
-    Optional<String> namespaces;
+    Optional<DeprecatedString> namespaces;
 };
 
 static OwnPtr<StateMachine>
@@ -232,9 +232,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return 0;
 }
 
-HashTable<String> actions(StateMachine const& machine)
+HashTable<DeprecatedString> actions(StateMachine const& machine)
 {
-    HashTable<String> table;
+    HashTable<DeprecatedString> table;
 
     auto do_state = [&](State const& state) {
         if (state.entry_action.has_value())
@@ -296,7 +296,7 @@ void output_header(StateMachine const& machine, SourceGenerator& generator)
 {
     generator.set("class_name", machine.name);
     generator.set("initial_state", machine.initial_state);
-    generator.set("state_count", String::number(machine.states.size() + 1));
+    generator.set("state_count", DeprecatedString::number(machine.states.size() + 1));
 
     generator.append(R"~~~(
 #pragma once
diff --git a/Meta/Lagom/Tools/ConfigureComponents/main.cpp b/Meta/Lagom/Tools/ConfigureComponents/main.cpp
index 052d2d1ec1..c499ceff2f 100644
--- a/Meta/Lagom/Tools/ConfigureComponents/main.cpp
+++ b/Meta/Lagom/Tools/ConfigureComponents/main.cpp
@@ -4,11 +4,11 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/LexicalPath.h>
 #include <AK/QuickSort.h>
 #include <AK/Result.h>
-#include <AK/String.h>
 #include <AK/StringView.h>
 #include <AK/Vector.h>
 #include <LibCore/ConfigFile.h>
@@ -25,18 +25,18 @@ enum class ComponentCategory {
 };
 
 struct ComponentData {
-    String name;
-    String description;
+    DeprecatedString name;
+    DeprecatedString description;
     ComponentCategory category { ComponentCategory::Optional };
     bool was_selected { false };
-    Vector<String> dependencies;
+    Vector<DeprecatedString> dependencies;
     bool is_selected { false };
 };
 
 struct WhiptailOption {
-    String tag;
-    String name;
-    String description;
+    DeprecatedString tag;
+    DeprecatedString name;
+    DeprecatedString description;
     bool checked { false };
 };
 
@@ -77,7 +77,7 @@ static Vector<ComponentData> read_component_data(Core::ConfigFile const& config_
     return components;
 }
 
-static Result<Vector<String>, int> run_whiptail(WhiptailMode mode, Vector<WhiptailOption> const& options, StringView title, StringView description)
+static Result<Vector<DeprecatedString>, int> run_whiptail(WhiptailMode mode, Vector<WhiptailOption> const& options, StringView title, StringView description)
 {
     struct winsize w;
     if (ioctl(0, TIOCGWINSZ, &w) < 0) {
@@ -97,7 +97,7 @@ static Result<Vector<String>, int> run_whiptail(WhiptailMode mode, Vector<Whipta
     int read_fd = pipefd[0];
     int write_fd = pipefd[1];
 
-    Vector<String> arguments = { "whiptail", "--notags", "--separate-output", "--output-fd", String::number(write_fd) };
+    Vector<DeprecatedString> arguments = { "whiptail", "--notags", "--separate-output", "--output-fd", DeprecatedString::number(write_fd) };
 
     if (!title.is_empty()) {
         arguments.append("--title");
@@ -116,13 +116,13 @@ static Result<Vector<String>, int> run_whiptail(WhiptailMode mode, Vector<Whipta
     }
 
     if (description.is_empty())
-        arguments.append(String::empty());
+        arguments.append(DeprecatedString::empty());
     else
-        arguments.append(String::formatted("\n {}", description));
+        arguments.append(DeprecatedString::formatted("\n {}", description));
 
-    arguments.append(String::number(height));
-    arguments.append(String::number(width));
-    arguments.append(String::number(height - 9));
+    arguments.append(DeprecatedString::number(height));
+    arguments.append(DeprecatedString::number(width));
+    arguments.append(DeprecatedString::number(height - 9));
 
     // Check how wide the name field needs to be.
     size_t max_name_width = 0;
@@ -133,7 +133,7 @@ static Result<Vector<String>, int> run_whiptail(WhiptailMode mode, Vector<Whipta
 
     for (auto& option : options) {
         arguments.append(option.tag);
-        arguments.append(String::formatted("{:{2}}    {}", option.name, option.description, max_name_width));
+        arguments.append(DeprecatedString::formatted("{:{2}}    {}", option.name, option.description, max_name_width));
         if (mode == WhiptailMode::Checklist)
             arguments.append(option.checked ? "1" : "0");
     }
@@ -151,7 +151,7 @@ static Result<Vector<String>, int> run_whiptail(WhiptailMode mode, Vector<Whipta
         return -1;
     }
 
-    auto full_term_variable = String::formatted("TERM={}", term_variable);
+    auto full_term_variable = DeprecatedString::formatted("TERM={}", term_variable);
     auto colors = "NEWT_COLORS=root=,black\ncheckbox=black,lightgray";
 
     char* env[3];
@@ -194,11 +194,11 @@ static Result<Vector<String>, int> run_whiptail(WhiptailMode mode, Vector<Whipta
 
     auto file = Core::File::construct();
     file->open(read_fd, Core::OpenMode::ReadOnly, Core::File::ShouldCloseFileDescriptor::Yes);
-    auto data = String::copy(file->read_all());
+    auto data = DeprecatedString::copy(file->read_all());
     return data.split('\n');
 }
 
-static bool run_system_command(String const& command, StringView command_name)
+static bool run_system_command(DeprecatedString const& command, StringView command_name)
 {
     if (command.starts_with("cmake"sv))
         warnln("\e[34mRunning CMake...\e[0m");
@@ -274,7 +274,7 @@ int main()
     StringView build_type = customize ? type.substring_view(7) : type.view();
 
     // Step 4: Customize the configuration if the user requested to. In any case, set the components component.is_selected value correctly.
-    Vector<String> activated_components;
+    Vector<DeprecatedString> activated_components;
 
     if (customize) {
         Vector<WhiptailOption> options;
@@ -336,12 +336,12 @@ int main()
     }
 
     // Step 5: Generate the cmake command.
-    Vector<String> cmake_arguments = { "cmake", "../..", "-G", "Ninja", "-DBUILD_EVERYTHING=OFF" };
+    Vector<DeprecatedString> cmake_arguments = { "cmake", "../..", "-G", "Ninja", "-DBUILD_EVERYTHING=OFF" };
     for (auto& component : components)
-        cmake_arguments.append(String::formatted("-DBUILD_{}={}", component.name.to_uppercase(), component.is_selected ? "ON" : "OFF"));
+        cmake_arguments.append(DeprecatedString::formatted("-DBUILD_{}={}", component.name.to_uppercase(), component.is_selected ? "ON" : "OFF"));
 
     warnln("\e[34mThe following command will be run:\e[0m");
-    outln("{} \\", String::join(' ', cmake_arguments));
+    outln("{} \\", DeprecatedString::join(' ', cmake_arguments));
     outln("  && ninja clean\n  && rm -rf Root");
     warn("\e[34mDo you want to run the command?\e[0m [Y/n] ");
     auto character = getchar();
@@ -351,7 +351,7 @@ int main()
     }
 
     // Step 6: Run CMake, 'ninja clean' and 'rm -rf Root'
-    auto command = String::join(' ', cmake_arguments);
+    auto command = DeprecatedString::join(' ', cmake_arguments);
     if (!run_system_command(command, "CMake"sv))
         return 1;
     if (!run_system_command("ninja clean"sv, "Ninja"sv))
diff --git a/Meta/Lagom/Tools/IPCMagicLinter/main.cpp b/Meta/Lagom/Tools/IPCMagicLinter/main.cpp
index ee7697eb73..5c482fc1fd 100644
--- a/Meta/Lagom/Tools/IPCMagicLinter/main.cpp
+++ b/Meta/Lagom/Tools/IPCMagicLinter/main.cpp
@@ -21,10 +21,10 @@ int main(int argc, char** argv)
     }
 
     // Read files, compute their hashes, ignore collisions for now.
-    HashMap<u32, Vector<String>> inverse_hashes;
+    HashMap<u32, Vector<DeprecatedString>> inverse_hashes;
     bool had_errors = false;
     for (int file_index = 1; file_index < argc; ++file_index) {
-        String filename(argv[file_index]);
+        DeprecatedString filename(argv[file_index]);
         auto file_or_error = Core::File::open(filename, Core::OpenMode::ReadOnly);
         if (file_or_error.is_error()) {
             warnln("Error: Cannot open '{}': {}", filename, file_or_error.error());
@@ -32,9 +32,9 @@ int main(int argc, char** argv)
             continue; // next file
         }
         auto file = file_or_error.value();
-        String endpoint_name;
+        DeprecatedString endpoint_name;
         while (true) {
-            String line = file->read_line();
+            DeprecatedString line = file->read_line();
             if (file->error() != 0 || line.is_null())
                 break;
             if (!line.starts_with("endpoint "sv))
diff --git a/Meta/Lagom/Wasm/js_repl.cpp b/Meta/Lagom/Wasm/js_repl.cpp
index cb798241bf..316279f186 100644
--- a/Meta/Lagom/Wasm/js_repl.cpp
+++ b/Meta/Lagom/Wasm/js_repl.cpp
@@ -50,7 +50,7 @@ EM_JS(void, user_display, (char const* string, u32 length), { globalDisplayToUse
 template<typename... Args>
 void display(CheckedFormatString<Args...> format_string, Args const&... args)
 {
-    auto string = String::formatted(format_string.view(), args...);
+    auto string = DeprecatedString::formatted(format_string.view(), args...);
     user_display(string.characters(), string.length());
 }
 
@@ -269,7 +269,7 @@ JS_DEFINE_NATIVE_FUNCTION(ReplObject::print)
 {
     auto result = ::print(vm.argument(0));
     if (result.is_error())
-        return g_vm->throw_completion<JS::InternalError>(String::formatted("Failed to print value: {}", result.error()));
+        return g_vm->throw_completion<JS::InternalError>(DeprecatedString::formatted("Failed to print value: {}", result.error()));
 
     displayln();
 
@@ -298,7 +298,7 @@ public:
     // 2.3. Printer(logLevel, args[, options]), https://console.spec.whatwg.org/#printer
     virtual JS::ThrowCompletionOr<JS::Value> printer(JS::Console::LogLevel log_level, PrinterArguments arguments) override
     {
-        String indent = String::repeated("  "sv, m_group_stack_depth);
+        DeprecatedString indent = DeprecatedString::repeated("  "sv, m_group_stack_depth);
 
         if (log_level == JS::Console::LogLevel::Trace) {
             auto trace = arguments.get<JS::Console::Trace>();
@@ -320,7 +320,7 @@ public:
             return JS::js_undefined();
         }
 
-        auto output = String::join(' ', arguments.get<JS::MarkedVector<JS::Value>>());
+        auto output = DeprecatedString::join(' ', arguments.get<JS::MarkedVector<JS::Value>>());
         switch (log_level) {
         case JS::Console::LogLevel::Debug:
             displayln("{}{}", indent, output);