Without looking too deeply into it, I assume it's MIDI and using some JS implementation of a MIDI engine / soundfont to play. https://developer.mozilla.org/en-

Without looking too deeply into it, I assume it's MIDI and using some JS implementation of a MIDI engine / soundfont to play. https://developer.mozilla.org/en-US/docs/Web/API/Web_MIDI_API https://developer.mozilla.org/en-US/docs/Web/API/Web_MIDI_AP...