Play hand gesture music in your browser.
Gesture Synth Weld is a free gesture synthesizer for playing music with hand gestures. Wave your hands in front of the webcam — or drag your mouse — and the instrument maps every motion to pitch and tone. No download, no account, nothing uploaded.
- Input
- Webcam hands, mouse or touch
- Engine
- Web Audio · WebAssembly tracking
- Output
- 2 voices · chords · 15s video clip
Move here to preview notes.
Press & hold (or pinch) to sound them.
How the gesture synthesizer works
Three steps between you and your first hand-played melody. The whole gesture synth runs in this tab — the camera model, the sound engine, and the recorder never touch a server.
Pick your input
Press Start Camera to track both hands with the webcam, or press Use Mouse Mode to play the same pitch field with a pointer. On a phone, touch mode is the default — no camera needed.
Move to shape the sound
Slide left to right to climb the scale, up and down to open or darken the filter. The gesture synth quantizes every position to the key and scale you chose, so each landing note is in tune.
Gate notes with a pinch
In camera mode, touch your thumb and index finger together to sound a note and release to stop it. With a mouse, press and hold instead. Two hands — or two fingers — play two voices at once.
The gesture map: where movement becomes music
- X axis → pitch
- Horizontal hand position selects the note. The field spans two octaves of your chosen scale, and positions snap to scale degrees so hand gesture music always lands in key.
- Y axis → filter brightness
- Vertical position sweeps a low-pass filter from about 180 Hz to 7.5 kHz. Raise your hand for a bright, open tone; lower it for a dark, muffled one. The live readout shows the filter percentage.
- Pinch → note gate
- Thumb-to-index distance opens and closes the envelope with hysteresis, so notes trigger cleanly without flickering. A generous dead zone keeps sustained notes stable while you move.
Voices, scales, chords and guided songs
A gesture synth should feel like an instrument, not a demo. Tune the engine to the song in your head — then take it anywhere, webcam or not.
Four waveform presets
Each preset pairs two detuned oscillators with its own envelope and filter character:
- Ember — soft triangle warmth for slow melodies
- Glass — clear sine bells with a high sparkle
- Circuit — hollow retro square-wave bite
- Reed — gritty sawtooth lead for solos
12 keys × 3 scales
Choose any of the twelve root keys, from C to B, and one of three scales: major pentatonic (five safe notes, impossible to sound wrong), full major, or natural minor for a moodier palette. The pitch field re-quantizes instantly.
Mouse & touch mode
No webcam, denied permission, or a phone in your hand — the full gesture synthesizer still works. Move the pointer to preview, press and hold to gate a note, and add a second finger for the harmony voice.
Learn a song note by note
The gesture synth's Guided mode walks you through public-domain melodies like Twinkle Twinkle Little Star and Ode to Joy. A glowing zone on the pitch field shows exactly where the next note lives; gate it with a press or a pinch and the lesson advances. Root and scale lock to C major, then restore when you exit.
Chord mode for instant harmony
Flip the Chord toggle and every gated note blooms into a diatonic triad — root, third, and fifth stacked from the scale itself, so major positions sound major and minor positions sound minor. Two hands play two chords at once; the big display reads the chord name, like C maj or E min.
A 15-second video of your take
The gesture synthesizer's Record 15s captures a branded video clip — live waveform, your current note or chord, and a gesture-synth-weld.net watermark — together with the synth's sound. Everything is rendered and saved on your device; preview it in the page or download the file.
Camera privacy: your video never leaves the tab
A camera instrument only works if you can trust it. Gesture Synth Weld is built local-first: when you press Start Camera, the browser loads a hand-tracking model and runs it in a WebAssembly sandbox inside this page. Every frame is analyzed on your own CPU or GPU and discarded the moment your hand position is read.
- No upload. Video frames are never sent over the network — the page makes no recording or streaming calls at all.
- No storage. Nothing from the camera is written to disk, cookies, or local storage.
- No microphone. The instrument asks for video only; audio input is never requested. Sound is synthesized, not captured.
- No background access. Stop Camera releases the device immediately, and closing the tab ends everything.
- Offline-friendly tracking. Once the model file is cached, hand tracking keeps working even if your connection drops.
The 15-second recorder renders a video clip of your take — waveform, note names, and watermark — with the synthesized sound, saves it as a file on your device, and never transmits it. Read the full privacy policy for details.
Gesture synth questions, answered
What is a gesture synth?
A gesture synth (short for gesture synthesizer) is an instrument that turns body movement into sound. Gesture Synth Weld maps your hand position to musical notes and filter brightness, so moving your hand through the air — or dragging a mouse — plays melodies in real time.
Is my camera video uploaded anywhere?
No. Hand tracking runs entirely in your browser using WebAssembly and the MediaPipe runtime. Video frames are analyzed locally on your device and are never sent to a server, recorded, or stored. The microphone is never requested.
Can I play without a webcam?
Yes. Mouse and touch mode gives you the same pitch field: move the pointer to choose a note, then press and hold (or touch) to sound it. A second finger on a touchscreen plays a second, independent voice.
Do I need to download or install anything?
No. Gesture Synth Weld is a web instrument: everything runs in the browser tab. There is no app, plugin, account, or sign-up — open the page and start playing.
Why do I have to press a button before any sound plays?
Browsers block audio until you interact with a page. Pressing Start Camera or Use Mouse Mode unlocks the Web Audio context in the same gesture, so the first note you play is already audible.
Which browser works best?
The latest Chrome or Edge on desktop gives the smoothest hand tracking. Safari and Firefox fully support mouse, touch, and audio; camera tracking works too but may run a little slower on older hardware.
Does it work on phones?
Yes. On a phone, use touch mode: drag one finger for pitch and filter, add a second finger for the harmony voice. Camera hand tracking is supported on mobile browsers, though a laptop or desktop webcam is steadier.
Can I record what I play?
Yes. Press Record 15s and the instrument captures up to fifteen seconds of video — a live waveform, your current note or chord, and a gesture-synth-weld.net watermark — together with the synth's sound. The clip is saved on your device only (as .mp4 or .webm depending on your browser) — preview it in the page or download it; nothing is uploaded.
Can it teach me a song?
Yes. Guided mode walks you through a melody one note at a time: a glowing zone on the pitch field shows where the next note lives, and pressing or pinching inside it advances the lesson. Two public-domain songs are included — Twinkle Twinkle Little Star and Ode to Joy — with a progress counter, a restart button, and a completion prompt to record your run.
Can I play chords?
Yes. The Chord toggle turns every gated note into a diatonic triad built from the current scale — root, third, and fifth — so major positions sound major and minor positions sound minor automatically. With two hands (or two fingers) you can play two chords at once, and the display shows the chord name, like C maj or E min.
Is Gesture Synth Weld really free?
Yes. The gesture synthesizer is free to use with no account and no feature paywall. The site may show unobtrusive ads in the future to cover hosting costs.
Play your first hand gesture melody in under a minute.
Scroll up, press Start Camera or Use Mouse Mode, and move. The gesture synth is loaded, tuned, and waiting — free, local, and yours.
Start playing now