Artificial Intelligence has unlocked the access to the text of medieval manuscripts! The partners of the European research project HIMANIS (Historical MANuscript Indexing for user-controlled Search) implemented, for the first time, the indexing and plain text querying of medieval manuscripts (199 registers and formularies, 80'000+ pages, written in the French royal chancery during the 14th and 15th centuries). The large scale of the corpus and the possibility to search in plain text for handwritten sources are unheard of in medieval studies. The challenge of multilingualism, script variation and abbreviations, which are crucial for HTR on medieval sources, has been successfully met, as well as writer identification.