Really cool app. It seems that the MIDI goes way faster than the exported song and goes out of sync quickly :(
hii ty ! ive never seen that happen, can u tell me what daw u exported the midi with and what json converter u used? ive only had this happen when i had tempo changes in my track and the converter i tried ignored them, but this converter should work fine: https://tonejs.github.io/Midi/
I'm using the converter you linked to. I am using Ableton Live, which tbf has midi export capabilities but for just one track. I exported one track, but it seems to be out of sync. I then exported each track, converted each track and then copied each track object to a single file to have all tracks, they seem to appear fine together, but still the out of sync makes me sad.