Gesture Synth (onrender)

This version of Gesture Synth lets you play chords with your hands in front of a camera. It is the only one in the category that names a loop pedal, MIDI output and harmony-aware visuals.

A loop pedal is what lets you layer a part over itself rather than playing one pass, and MIDI means the notes can leave the browser and go into whatever you actually produce in. Together those two make it the most production-oriented option here.

The site publishes very little beyond that. There is no pricing, no control reference and no detail on how the MIDI output works, so you find out by opening it.