VST3 plugin · MIT licence

MIDI Chord Detector

v3.1.0 Free & open source Windows · macOS

Play a chord and see its name. MIDI Chord Detector listens to the MIDI going into your DAW and names the chord in real time, from simple triads to altered 13ths, with the inversion, voicing and notation alongside.

Download v3.1.0 View on GitHub

MIDI Chord Detector in Cubase showing Fsus4 in drop-2 voicing, the notes on a grand staff, the active notes and a highlighted piano keyboard

60+ chord patterns

Triads, 6ths, 7ths, 9ths, 11ths and 13ths, altered dominants, add chords and quartal voicings, matched by interval pattern with weighted scoring.

Inversions & voicings

Slash-chord notation for inversions (Auto, Always or Never) and voicing detection: close, open, drop-2, drop-3 and rootless.

See what you play

An 88-key keyboard, a grand-staff notation panel and an active notes monitor. Each panel can be toggled on or off.

Real-time safe

No allocations on the audio thread, zero added latency, and confidence scoring that keeps the chord name from flickering.

Sustain-aware

Respects the sustain pedal (CC64), so held notes count the way you'd expect when you play naturally.

MIDI pass-through

Your MIDI goes straight on to the next instrument. Built as a VST3 Instrument, so it also works in Cubase AI and Elements.

Get started

Download the VST3 (or the standalone app) from the latest release.
Install: extract MIDI Chord Detector.vst3 to C:\Program Files\Common Files\VST3\ (Windows) or ~/Library/Audio/Plug-Ins/VST3/ (macOS), then rescan plugins.
Load it as a VST3 Instrument and route its MIDI output to a sound-generating instrument.
Play two or more notes. The chord name appears as you play.

Requirements

Format	VST3 Instrument, plus a standalone app
Windows	Windows 10 or 11
macOS	macOS 11 or newer (build from source)
Tested in	Cubase AI 13 (Windows), Ableton Live (macOS)
Should work in	FL Studio, Reaper, Studio One, Logic Pro (via bridging)
Licence	MIT, built with JUCE

Supported chords

Major
Minor
dim
aug
sus2
sus4
5
maj7
7
m7
m(maj7)
dim7
m7♭5
aug7
+maj7
7sus4
6
m6
6/9
m6/9
maj9
9
m9
maj11
11
m11
maj13
13
m13
7♭5
7♯5
7♭9
7♯9
7♯11
7alt
9♯11
13♭9
add9
m(add9)
add11
add♯11
Quartal

Changelog

3.1.0May 25, 2026
Full piano keyboard, grand-staff notation panel and active notes monitor, all toggleable. Sustain pedal (CC64) fix.
3.0.0Jan 29, 2026
New pattern-based detection engine replaces the legacy algorithm: more accurate recognition of complex chords and clearer harmonic interpretation.
2.0.0Jan 26, 2026
Better accuracy, smoother chord transitions, multi-factor confidence scoring and less flickering.
1.0.0Jan 25, 2026
First public release as a VST3 Instrument.

All releases on GitHub →