A gesture synth app for iPhone: Musaic and Gesture Synth compared
Gesture Synth is a free instrument by Eric Wei that runs in a web browser: you show hand shapes to a webcam and it plays chords. Musaic is an iPhone and iPad app with an instrument called Chords that works the same way. The left hand picks the chord, the right hand shapes it. Musaic also films you while you play, records your singing on its own layer and has six more instruments you play in the air. Both are free.
Musaic - Recording Studio is free for iPhone and iPad, and so are the Air instruments.
| Musaic (Chords) | Gesture Synth | |
|---|---|---|
| Where it runs | ||
| Platform | iPhone and iPad app | Web browser |
| Camera | The iPhone's front camera | A webcam or device camera |
| Price | Free | Free |
| Playing chords | ||
| Left hand | Number of fingers picks the chord, I to VII; a fist is a rest | Finger shapes pick the chord, I to VII; tilting picks major or minor |
| Right hand | One to four fingers for the voicing | Finger count for the chord type: triad, first inversion, sevenths |
| Octave | Thumb for an octave lower | Thumb for an octave higher or lower |
| Volume | Height of the right hand | Height of the right hand |
| Filter | Not in the instrument | Tilt of the right hand |
| Other air instruments | Six more: Penta, Halo, Theremin, Bellows, Handpan, Rails | Not advertised |
| Recording | ||
| Records what you play | Yes, every take becomes a layer | Not advertised |
| Films you while you play | Yes, in a video project | Not advertised |
| Your singing | Recorded on its own layer called Voice | Not advertised |
| Play over a song | Yes, earlier takes play back while you record, up to 10 layers | Not advertised |
| Export | Video in 1080p or 4K, the mix as .m4a, every layer separately. Watermark in the free version, removed with Pro | Not advertised |
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Seven air instruments
Chords, plus Penta (a note on every finger), Halo (a ring of notes around your palm), Theremin, Bellows, Handpan and Rails. How each one is played.
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A video of you playing
In a video project the camera films you while it reads your hands, so the take is a clip for Reels, TikTok or Shorts, not only sound.
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Sing while you play
Your voice lands on its own layer, with its own effects, next to the instrument.
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A whole song
Record the chords first, then a melody, a harmony or a guitar on top, up to 10 layers, and put them side by side in one of 77 layouts.
Gesture Synth needs no install: open the page in a browser, allow the camera and play, also on a laptop or an Android phone. Its right hand also sweeps a filter by tilting. Musaic runs only on iPhone and iPad. And Gesture Synth is the original: Eric Wei's chord language is what made playing chords with your hands go viral, and Musaic's Chords instrument follows the same idea.
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Is there a Gesture Synth app for iPhone?
Gesture Synth itself runs in a web browser and has no app in the App Store. Musaic is an iPhone and iPad app with an instrument called Chords that is played the same way: the left hand shows the chord, the right hand shapes it. Musaic also records the video and your voice while you play.
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How do you play chords with your hands in Musaic?
Open Add layer, Air instruments and choose Chords. Your left hand picks the chord by the number of fingers you show, from I to VII, and a fist is a rest. Your right hand shapes it: one to four fingers for the voicing, the thumb for an octave lower, the height of the hand for the volume.
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Is it free?
Yes. The Air instruments are free in Musaic, like the other instruments. Musaic Pro removes the watermark from the exported video and adds lyrics, animations and chord detection. Gesture Synth is free as well.
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Does Musaic need a special camera?
No. It uses the iPhone's front camera, so you see yourself while you play. The hand tracking runs on the iPhone itself, with Apple's Vision framework.
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Can I sing while I play?
Yes. In Musaic your voice lands on its own layer called Voice, next to the instrument, so you can mix the two later. In a video project the camera films you at the same time.
Musaic - Recording Studio is free on the App Store for iPhone and iPad, and so are the Air instruments. Musaic Pro removes the watermark from the exported video and adds lyrics, animations and chord detection.
Gesture Synth: the instrument itself and Eric Wei's page about it, read on 12 October 2026. Gesture Synth is Eric Wei's project. This page is mine and not connected to him. If something here is out of date, tell me and I will fix it.