ChordLens
Free & open source

See the chords
you play.

ChordLens listens to your keyboard — hardware MIDI, your computer keys, or the on-screen piano — and names the chord instantly, right above a live grand staff.

Download Latest release All platforms
  • macOS
  • Windows
  • Android
  • No account needed
ChordLens showing a Cmaj7 chord on the grand staff and highlighted piano keys

Everything on one screen

No menus to dig through while your hands are on the keys.

Cmaj7

Real time chord detection

Play anything and the chord name appears immediately — triads, sevenths, extensions, suspensions and altered voicings.

𝄞

Live grand staff

Every pressed note is notated on treble and bass clefs, respecting the key signature you select.

🎛️

MIDI input

Connect a MIDI keyboard and ChordLens auto-connects to the first available device. Or use the computer keyboard mapping.

✨

Chord & scale highlighting

Pick a chord or scale from the menu and the matching keys light up across the keyboard — great for practice.

🔁

Chord progressions

Build a progression and loop it in time with the metronome, one chord per bar, with optional voice leading.

⏱️

Metronome

A metronome in the top bar that works anywhere in the app, with adjustable BPM, a visual beat and a mutable click.

🔊

SoundFont playback

Ships with a Rhodes SF2, loads your own SoundFont files, and has a mute mode when you only want the analysis.

⌨️

Keyboard mapping

Z S X D C V G B H N J M , L . ; / plays the octave, [ and ] shift it up and down, Space starts and stops the metronome.

Try the chord detection

Click or tap the keys — or use your computer keyboard, just like in the app.

Detected chord
—
Play two or more notes

A simplified taste of the real thing. The app detects far more chord types, on a full 88-key range.

A closer look

Chords, scales, progressions and settings — all a tap away.

Chord picker highlighting C minor 7 over a played Cmaj7
Chord highlighting
Scale picker highlighting C harmonic minor
Scale highlighting
A Cmaj7 – Dm7 – G7 progression playing in time with the metronome
Progressions & playback
Editing a chord in a progression with the root and quality picker
Editing a progression
Compact mobile layout showing a Cmaj7 chord
Mobile layout
Settings menu
Settings & SoundFonts

Download ChordLens

Always the latest release, straight from GitHub.

Installation notes
  • macOS — the DMG is unsigned. On first launch, right-click the app and choose Open, or run xattr -dr com.apple.quarantine /Applications/ChordLens.app.
  • Windows — SmartScreen may warn about an unknown publisher. Choose More info → Run anyway.
  • Android — sideloading the APK requires allowing installs from unknown sources.

Prefer to build it yourself? Clone the repo, run flutter pub get, then flutter run -d macos|windows|android. Requires a Flutter SDK compatible with Dart 3.9.