Two hands. One browser instrument.
What Is a Gesture Synth?
Play a free gesture synth online with your webcam. The webcam gesture synth on this page turns a standard webcam into a responsive musical synth. Move both hands in front of the camera to make music: play chords, shape harmony, control volume and tone, change octave, or perform continuous melodies in Theremin mode. Everything runs directly in your browser, so you can begin without installing software, creating an account or connecting a MIDI controller.
The synth above is the complete experience, not a preview. Start a private camera session, choose a mode, and use the guide below whenever you want a clearer explanation of each control.
Play the instrument ↑- Control
- Two-hand tracking
- Sound
- Web Audio synthesis
- Privacy
- Camera processed locally
- Cost
- Free, no account
A Browser Instrument Controlled by Movement
A webcam gesture synth is a synthesizer controlled through physical movement instead of a piano keyboard, mouse or touchscreen. This gesture synth uses webcam hand tracking to translate finger positions, hand height and wrist angle into musical controls. The result is an instrument that responds to natural movement while still providing repeatable chord and sound choices.
Unlike a simple motion-triggered sound effect, the synth continuously interprets both hands. Your left hand chooses harmonic information, while your right hand changes how that harmony sounds. You can move between scale degrees, inversions, seventh chords, filters, octaves and dynamic levels in one performance.
Audio is generated in real time with the Web Audio API. The camera is used to locate hand landmarks, and those landmarks become values for the synthesizer. You do not need microphone access because the synth creates sound rather than recording it.
Explore the Web Audio API on MDN ↗ · See how MediaPipe hand landmark detection works ↗
How to Play Music with Hand Gestures
Select Start and allow camera access when your browser asks for permission. Place your upper body and both hands inside the frame. The status indicators show whether the left hand and right hand are currently detected, so you can correct your position before attempting a chord.
Hand tracking works best when your palms and fingers are clearly separated from the background. Give each shape a brief moment to stabilize before changing position. The synth uses smoothing and a short lost-frame tolerance to reduce rapid musical changes caused by tracking noise.
Left-hand chord controls
In Gesture mode, the left hand chooses the harmonic degree. Holding up one to five fingers selects degrees I through V. The index-and-little-finger shape selects degree VI, while adding the thumb selects degree VII. The scale guide highlights the active degree and shows the notes available in the selected key.
When major and minor selection is assigned to wrist control, tilting the left wrist changes the chord world. You can also lock the choice in Settings when you want predictable major or minor harmony for practice or loop recording. Changing the key recalculates the available notes without changing the hand-control layout.
Right-hand harmony and expression controls
The right hand does more than control volume. Its height changes the output level, while the number of raised fingers changes the harmony style. Different shapes select a triad, an inversion or a seventh-chord variation, allowing one left-hand degree to produce several musical colours.
Tilting the right wrist changes the low-pass filter, moving the sound between darker and brighter tones. Extending the thumb outward lowers the harmony by an octave. These controls work together: select a degree with the left hand, raise the right hand for more volume, open additional fingers for a richer chord and tilt the wrist to soften high frequencies.
Musical parameters are smoothed to reduce clicks and abrupt jumps. If the output becomes too strong, use the master mute button for an immediate stop or lower the master volume in Settings before continuing.
Gesture Mode and Theremin Mode
Gesture mode is designed for chords and harmonic performance. It is the best place to explore progressions, compare chord qualities and record structured loops. Both hands work together: the left hand chooses the musical foundation and the right hand shapes its harmony, volume, filter tone and octave.
Theremin mode changes the page into a continuous-pitch synth. The vertical position of the right hand controls pitch across an exponential frequency range, while the left-hand height controls volume. Move slowly for smooth glides or make wider movements for dramatic pitch changes.
Because Theremin mode does not lock every gesture to a chord, small changes can produce audible pitch differences. Begin with slow motions, watch the frequency readout and learn the available range before attempting faster melodies. You can switch back to Gesture mode at any time without restarting the camera.
Build Music with the Four-Track Loop Sequencer
Enable the Loop Sequencer in Settings to arrange a performance across four independent tracks. Choose a tempo from 30 to 300 BPM, use Tap Tempo, select the number of measures and set a time signature such as 3/4, 4/4, 5/4, 6/8 or 7/8.
Recording begins after a one-measure count-in. Played events are quantized to the sequencer grid and repeat when the loop reaches the end. Each track has its own level, mute and solo controls, making it possible to build a progression one layer at a time and then balance the parts.
The grid can also be edited directly. Draw events into empty steps, clear unwanted notes or choose degrees I through VII for individual cells. When the arrangement is finished, export it as a WAV file. Browsers without the required offline-audio support can use the WebM fallback. Audio rendering and download happen locally.
Learn Songs One Hand Shape at a Time
Learn mode provides guided practice for public-domain melodies including Twinkle Twinkle Little Star, Ode to Joy and Amazing Grace. Select a song from the local library and follow the target degree, chord quality and octave shown on screen.
Hold the correct position steadily to complete each event. The practice view records successful notes, missed attempts and completion time without requiring an account. Repeat a section, skip an event, enable the metronome or restart the exercise whenever you want to practise at a different pace.
Songs can also be opened with a direct link using the song parameter in the URL, so you can bookmark an exercise and return to the same practice screen later.
Private Camera Processing in Your Browser
Gesture Synth requests camera permission only after you select Start. It requests a video track but does not request microphone access. Webcam frames are processed inside the browser for hand-landmark detection and are not stored as recordings or uploaded to our servers.
Stopping the session releases the active camera track. You can also revoke camera permission through the site controls beside your browser address bar. The page stores only preferences such as the selected key, tutorial completion and sequencer visibility in localStorage.
There are no user accounts, subscriptions, payment forms or uploaded performances in this version. Exported loops are created as local audio downloads. The separate privacy page explains the camera lifecycle, model files, browser storage and permission recovery in more detail.
Tips for Reliable Hand Tracking
Tracking quality depends on lighting, distance, camera angle and device performance. The following adjustments solve most detection problems without changing musical settings.
- Use soft front-facing light and avoid a bright window directly behind you.
- Keep both wrists, palms and fingertips inside the camera frame.
- Stand roughly one arm's length from the webcam.
- Choose a background that contrasts with your hands and clothing.
- Avoid placing one hand directly in front of the other.
- Enable low-performance mode if tracking or animation becomes slow.
- Use landscape orientation on mobile devices for more playing space.
- If permission was denied, reset camera access in the browser and reload the page.
- Select Stop session when finished so the camera is released immediately.
Browser and Device Support
Recent desktop versions of Chrome and Edge provide the primary experience because they offer reliable camera, WebAssembly and Web Audio support for the gesture synth. Chrome on Android is also supported, with a landscape reminder on smaller screens. Safari and iOS may use compatibility fallbacks depending on the available audio and graphics features.
If sound is silent, confirm the tab is not muted, raise the master volume gradually and interact with Start again so the browser can resume its AudioContext. If the camera is unavailable, close other video applications, check the browser permission and use a normal secure window rather than an embedded preview.
Questions before you play
Gesture Synth FAQ
Is the gesture synth free?
Yes. The synth, Theremin mode, practice songs and loop sequencer can be used without creating an account or purchasing a subscription.
How do I play a gesture synth online?
Allow camera access, select Start and move your hands in front of the webcam. You are playing a free gesture synth online with your webcam: the left hand selects chords while the right hand shapes harmony and tone.
Does the site record my camera?
No. Camera frames are processed locally for hand tracking and are never stored or uploaded.
Does it need microphone permission?
No. Sound is generated by the browser through the Web Audio API; the instrument never listens to or records your microphone.
Why does the right hand change the chord?
The right hand controls both expression and harmony. Finger count selects triads, inversions and seventh chords, while height, wrist angle and thumb position control volume, filter tone and octave.
Can I use only one hand?
Some controls can respond when one hand is visible, but Gesture mode is designed around coordinated two-hand performance. Theremin mode also uses one hand for pitch and the other for volume. A clear two-hand gesture gives you the full chord and expression set.
Can I save a performance?
The sequencer can export the current arrangement as a WAV file; browsers without audio-rendering support may use WebM instead.
Which browser works best?
Recent desktop Chrome and Edge are primary; Chrome on Android is supported with a landscape layout, while Safari may use compatibility fallbacks.
