Have you encountered the NEUTRINO Project already? Until now it has two older voice synchronizer, but the software is free. One has to write lyrics to a MIDI, for example with MuseScore and just run the .musicxml through the included .bat with a path edit, there is an AI included which tries to mimic an actual voice unlike for example basic UTAU or Vocaloid which have to be completly tweaked by humans. Well the problem is now I don't have that very much of knowledge of how music theory works (with lyrics) and one must be very good in Japanese, because that's the only language possible. Maybe there will be soon an English one added on top or more voice banks from known voice synthesizers.
https://www.youtube.com/watch?v=m7n5PfUGaT8 
