Play music first. JellyDazzle is audio-reactive — put something on before you watch it. Anything playing on your Mac will do. In silence it still runs, but on internal clocks, and you are seeing about half of what it does.
634 routines. Twenty-four written in hand-tuned ARM64 assembly, six hundred and ten more in C. 180 colour schemes, interpolated in OKLab. Free, and it collects nothing.
Download for macOS Browse every routine
What it does
Put on a record, a film, a livestream — anything at all — and the screen answers it. On macOS 14.2 and later JellyDazzle taps the system audio output, so it follows whatever app is playing rather than only what a microphone can hear.
Why it looks different
Most visualisers are one shader with a colour picker. This is an engine: fractals, plasmas, lightning, caustics, gears, weaves, nebulae, cellular growth — scheduled into layers by how much each routine moves on its own, so the stillest ones get the most transform and nothing sits static. Two routines from the same shape family never share the screen.
Two keys
| C | New colours. The palette jumps somewhere genuinely far from where it was — chosen at random among the most distant schemes, so it stays surprising. |
|---|---|
| S | New shapes. The whole cast retires and the stack fills again from the library. Colour is left alone. |
Neither one cuts. Nothing here strobes — that is the engine's one law, and a key press is not an exemption: colour changes crossfade, routines fade out under the same envelope that retires them normally, and the release gate measures it.
It knows nothing about you
No network code, no accounts, no analytics, no advertising. Audio is turned into numbers to drive the current frame and then discarded — never recorded, never stored, never transmitted. There is nothing in the app capable of sending it. Full policy.
Requirements
An Apple Silicon Mac (M1 or later) running macOS 12 or later. The rendering core is hand-written ARM64 assembly, so it does not run on Intel.
In tribute
JellyDazzle exists because of DAZZLE.EXE, written by James R. Shiflett of Houston, Texas — at night, “a sort of therapy,” as he called it. MicroTronics released it as shareware in 1990. This is an homage, not affiliated with the original. The full story.
Open source
MIT licensed, and the whole engine is public at github.com/LIBCSYS/JellyDazzle.