FreeMIDIChords is a free, open-source music theory tool suite that works with any MIDI keyboard — no installation required for the web version, no subscriptions, no paywalls.
Plug in any MIDI keyboard and it detects chords and intervals in real time
Visualizes them on staff notation, a piano keyboard, and an interactive circle of fifths
Works in reverse too — pick a chord and hear it played back through MIDI or built-in audio
Includes scales, and metronome
