KeyLens

The simplest way to build chord progressions and learn how to play them.

Build chord progressions that actually work.

All 7 Diatonic Chords, Color-Coded

Pick a key and instantly see every chord available to you, grouped by harmonic function. Know what fits, know why it fits — and make better creative decisions faster.

Chord Voicing Tools

Go beyond basic triads. Add extensions (7ths, 9ths), flip inversions, or borrow from parallel keys to shape exactly the sound you're after. Preview every variation before you commit.

Chord Bank and Chart View

Save up to 8 chords as you build your progression. The piano chart is always there when you need a quick visual reference on how to play for any chord in your progression on a Piano or MIDI Keyboard.