See a song's chords, key and Roman numerals

Play a recording with the chord timeline chordotomy wrote for it: a chord on every beat, its numeral and bass, and the secondary dominants and borrowed chords in colour.

1. Analyze the recording on your computer with chordotomy: chordotomy analyze song.mp3 writes song.chords.json next to it.
2. Open the recording and its .chords.json here.
3. Play. Turn on Play chords to check them by ear, correct a chord in the editor, and save the edited timeline.