mUltimate Chopin is a modern Internet platform presenting all the available sources of the works of Fryderyk Chopin. Developed by Paweł Kamiński, editor of the Chopin National Edition, in co-operation with the editorial team of the Fryderyk Chopin Institute as part of the Digital Heritage program. This application has been especially designed to enable browsing, analyzing and comparing digitalized sources, and offers instant access to commentaries on all the problematic places. System users are able to closely follow the editing process and make their own decisions (e.g. related to the choice of variants) on the basis of the photocopied sources made available.