Real-time MIDI chord detection means identifying the chord you are playing the moment you press the keys — with no manual input, no guessing and no delay. Here is how it works and what it means for keyboard players.
Real-time chord detection is the process of analyzing the notes being played on a MIDI keyboard and automatically identifying the chord name, inversion, chord type and harmonic function — while you are still playing. No buttons to press, no note entry. Just play, and the result appears.
For keyboard players, this bridges a gap that music theory books leave open: you can read about a Cmaj7 chord, but until you hear and see it identified while your hands are on the keys, the connection between name and sound is hard to internalize.
Modern browsers support MIDI input through the Web MIDI API. When you connect a USB MIDI keyboard, the browser can request access to the MIDI device and receive note data directly — no software installation needed.
When you press a key, your keyboard sends a MIDI message over USB. That message contains a note number (0–127, where 60 is middle C) and a velocity value. The browser receives this instantly, and an application like ChordBeam can process it in the same frame.
Chrome and Chromium-based browsers have the best Web MIDI support. Firefox requires a plugin. Safari does not currently support Web MIDI. If you are on a compatible browser, no setup beyond plugging in your keyboard is usually required.
Once ChordBeam has the active notes, it converts MIDI note numbers to pitch classes (ignoring octave), then compares the set of pitch classes against a library of known chord templates. The template that best matches — accounting for inversions and missing notes — becomes the detected chord.
This process runs every time a note is pressed or released, so the displayed chord updates immediately with each change to your voicing. Hold four notes → chord appears. Release one → chord updates or clears.
ChordBeam detects the chord from pitch classes, not absolute pitches. C–E–G in any octave arrangement is still C major. The inversion is determined separately by identifying the lowest note (the bass note) and comparing it to the chord root.
When you play a chord on your connected MIDI keyboard, ChordBeam surfaces:
Chord nameThe full chord name including quality — C major, Dm7, G#aug, Fsus2Note namesEvery pitch class in the chord spelled out — C, E, G, BbBass noteThe lowest active MIDI note — determines inversionInversionRoot position, 1st inversion or 2nd inversion — shown clearlyRoman numeralHarmonic function within your selected key — I, ii, V7, bVIIChord typeMajor, minor, dominant, diminished, augmented, suspendedEar training and theory study traditionally happen separately from playing. You read a concept, then try to apply it later. Real-time chord detection collapses that gap.
When you play a chord and see its name appear instantly, you are reinforcing the connection between sound, physical shape and music theory vocabulary at the same time. Over hundreds of repetitions, that connection becomes intuitive rather than intellectual.
This is particularly useful for church musicians learning gospel voicings, songwriters checking their chord quality, students studying inversions, and teachers who want to demonstrate harmonic concepts in real time during a lesson.
Getting started takes about 30 seconds:
Connect your MIDI keyboard to your computer with a USB cable.
Open ChordBeam in Chrome or a Chromium-based browser.
Click "Open Chord Detector" and allow MIDI access when prompted.
Play a chord — you will see the name appear immediately.
If your keyboard does not appear, check the MIDI setup guide for browser compatibility and troubleshooting tips.
Connect your MIDI keyboard and open the live detector. Play any chord and see the name, notes, inversion and Roman numeral appear instantly.
Identify chords by notes, bass and intervals — with or without a MIDI keyboard.
Start here — root, third, fifth, and the major/minor foundation.
Understand how ChordBeam identifies bass notes and inversion positions.
Step-by-step connection guide, browser compatibility, and troubleshooting.