About MIDIKeyboard.app

A free, browser-based companion for your MIDI keyboard.

MIDIKeyboard.app connects to a MIDI keyboard right in your web browser and shows you what you're playing in real time — the notes under your fingers, the chord they spell, and where that chord can go next. It's built for learners, songwriters, and anyone who wants to understand the harmony they're playing.

What it does

Live note & chord detection — plug in a MIDI keyboard and see each note highlighted and the chord named as you play.
Harmony helpers — suggested next chords and the seven diatonic chords in each key, to help you build progressions.
Chord reference — every diatonic chord in all 12 major keys, with keyboard diagrams, searchable and toggleable between sharps and flats.
Built-in sound — optional tones so you can hear what you play even without a connected instrument's own output.
Comfort options — adjustable octave range and key count, light and dark themes, and installable as an app (PWA) for offline use.

How it works

The app uses the browser's built-in Web MIDI support, so it works best in Chrome, Edge, and other Chromium-based browsers. Your MIDI input is read and interpreted entirely on your own device — nothing you play is uploaded anywhere. See the Privacy Policy for details.