SoundToMIDI

SoundToMIDI converts recorded audio into MIDI notes inside the browser. You drop in an MP3, WAV, FLAC, M4A, OGG, AAC, MP4 or WebM file of up to 100 MB, or record a melody for up to 60 seconds, and the notes are transcribed locally, so audio and filenames stay on the device. Users can select a short phrase to convert, such as 15 or 30 seconds, and choose a starting profile like general, voice, piano and guitar or bass.

Advanced settings cover onset confidence, note confidence, minimum note length and tempo. The result includes a free Raw MIDI file, and a paid Cleaned MIDI that applies adjustable cleanup, quantization to a grid, note range limits and transposition, with a piano roll preview and undo and redo. A compare view plays the original audio, the raw MIDI and the cleaned MIDI before you buy. The site notes that cleanup refines detected notes and does not run a more accurate model.