Chord synth
The classic gesture synth: diatonic chords in any key with four sounds (Warm, Bright, Retro, Strings), inversions and sevenths, and a beat to play along to.
Read the chord guide →A browser instrument · no install
Gesture Synth: play music with your hands
Start your webcam, raise a hand, and play chords or an air theremin. A free gesture synth that runs in your browser: no account, and no video ever leaves your device.
Ready
—
Camera stays on your device
Frames never leave your device. Best in Chrome or Edge on a laptop; Safari and phones fall back to touch if tracking is slow. Trouble?
How the gesture synth works
1
Allow the camera
Press Begin and accept the camera prompt. The hand tracking model loads once, then everything runs locally at your webcam's frame rate.
2
Left hand picks the chord
One to four fingers play chords I to IV, an open hand is V, index plus pinky is VI, and adding the thumb is VII. Lean the hand inward for minor. A fist is silence.
3
Right hand shapes the sound
Raise it for volume, pinch for brightness, and show one to four fingers for root position, inversions or a seventh. Only one hand? The synth voices the chord for you.
Two instruments, one webcam
Chords in one hand, melody in the air
Air theremin
Continuous pitch from your right hand, volume from your left, with note snap to a scale so it stays in tune, and pinch for vibrato.
Open the theremin →Why HandSynth
Made to be played, not just demoed
Works without a camera
Mouse, touch and keyboard modes play the same instrument, so it runs on any device and in any lighting.
No stuck notes
When a hand leaves the frame the chord releases within a fraction of a second instead of hanging.
MIDI out
Send chords, pitch bend and volume to Ableton, Logic, GarageBand or any synth over a virtual MIDI port.
Setup links
Copy a link with your mode, key, scale, sound and tempo so a guide or a friend opens exactly the same instrument.
Honest latency numbers
The stage shows tracking time and audio latency while you play.
Private by design
Frames are processed in your browser and discarded. There is nothing to upload to.
Learn
Guides
- How to Play Gesture Synth
Set up the camera, learn the left-hand chords and right-hand expression controls, and get your first progression in five minutes.
- Gesture Synth Chords: Degrees, Minor Tilt and Voicings
Every chord you can play with finger counts, how the minor tilt works, inversions and sevenths, and three progressions to practise.
- Gesture Synth Not Working? Camera, Sound and Tracking Fixes
Short fixes for a blocked camera, hands not detected, no sound on iPhone, low frame rate and browser problems.
- Gesture Synth on Mobile: iPhone and Android Setup
How the gesture synth works on iPhone and Android, what to expect from the front camera, and the touch fallback.
- How a Hand Tracking Synth Works in the Browser
MediaPipe hand landmarks, how they map to chords and pitch, the Web Audio chain, latency, and why no video leaves your device.
- Gesture-controlled instruments you can play in the browser
The source projects, Air Theremin, GestureGroove and more, compared side by side.
FAQ
Questions
- Does the gesture synth upload my camera video?
- No. Hand tracking runs inside your browser with MediaPipe compiled to WebAssembly. Frames never leave your device, and the site has no server that could receive them. Analytics counts page views only.
- Which browsers work?
- Chrome and Edge on a laptop or desktop give the smoothest tracking. Firefox works. Safari 17 and later works on Mac; on iPhone the camera runs but tracking can be slow, so the touch fallback kicks in. Every browser needs HTTPS for camera access.
- Why is there no sound on my iPhone?
- Check the silent switch on the side of the phone and tap Begin again; iOS only starts audio after a tap. Details are in the troubleshooting guide.
- Can I record what I play?
- Yes. Press Record, play, then press Stop to download a WAV file. Turn on the beat first if you want a click or a simple drum loop underneath.
- Can I use it as a MIDI controller?
- Yes, in Chrome or Edge on desktop. Press MIDI out, pick a port such as the macOS IAC Driver or loopMIDI on Windows, and your DAW receives the chords, theremin pitch bend and a volume CC.
- Is this the original Gesture Synth?
- No. HandSynth is an independent instrument written from scratch. The gesture synth idea comes from two open-source projects by Eric Wei and Ekmand, which we credit and link on the source projects page.