Baycomp is a library for Bayesian comparison of classifiers. Functions compare two classifiers on one or on multiple data sets. They compute three probabilities: the probability that the first classifier has higher scores than the second, the probability that differences are within the region of practical equivalence (rope), or that the second classifier has higher scores. We will refer to this probabilities as p_left, p_rope and p_right. If the argument rope is omitted (or set to zero), functions return only p_left and p_right.