Open Rack
A modular synthesizer you patch by hand. Drag cables between oscillators, filters, envelopes and mixers, and hear the result straight away. Nothing is installed and nothing is uploaded.
Open the rack →The first visit downloads about 4 MB, which your browser then caches. It works best on a desktop or laptop. It also runs on phones, but the panels are small there.
How to play
Browsers keep audio off until you tap. The rack opens with a short self-playing patch, so your first tap should bring in a gentle sequence.
Drag from one jack to another to connect them, then turn knobs to shape the sound. Drag a cable end away to remove it.
Right-click (or long-press) an empty space in the rack to browse and add modules. Use the menu to save a patch to your device.
Instruments
The modular rack: patch cables between modules and build your own sounds.
SYNTHSurge XT engineA deep polyphonic synth with 585 factory patches, eight macros and a playable keyboard.
SYNTHHelmA friendly polyphonic subtractive synth with free GPL and CC0 patches, our own panel and a playable keyboard.
What's in this build
| Collection | Modules | Licence |
|---|---|---|
| Cardinal host | Audio out, CV, MIDI, parameters, time, text notes | GPL-3.0-or-later code, CC0 art |
| Fundamental | VCO, VCF, VCA, ADSR, LFO, noise, quantizer, random, scope, mixer, merge/split, sum, mid/side | GPL-3.0-or-later |
| Bogaudio | VCO, VCF, VCA, LFO, AD, noise, offset, sample & hold, switches, unison | GPL-3.0-or-later code, CC-BY-SA-4.0 art |
| Aria Salvatrice | Spleet, Swerge (poly split/merge) | GPL-3.0-or-later code, CC-BY-SA-4.0 art |
| Valley | Dexter (FM oscillator), Interzone (synth voice) | GPL-3.0-or-later |
| Mockba Modular | CZ- and ladder-style oscillators, filter, mixer, panner, envelope, voltage adapter | MIT |
| Infinite-Noise | 85 utility modules: LFOs, envelopes, VCAs, manual triggers and CVs, mixers, matrix mixers, comparators, sample & hold, slew, crossfaders, poly tools, random and chaos, Turing machine, bits | GPL-3.0-or-later code, CC0 art (new) |
Left out on purpose
- Surge XT rack modules. The code is open source, but their panel art is licensed for non-commercial use only. The Surge XT engine page uses a new interface instead.
- Audible Instruments. Its artwork licence is not compatible with this release.
- Infinite-Noise panel art and logo, which are licensed for non-commercial use only. The 85 Infinite-Noise modules are included with plain new panels (CC0) that show each control's name.
- Rack's original knob, jack and switch graphics, also non-commercial. They are replaced with new artwork, drawn for ∞Open Rack and released as CC0.
- Built-in logos, panels and character art under non-commercial or no-derivatives licences. Those files are not shipped.
Good to know
- This is a preview. Expect rough edges.
- Audio runs on your device's main browser thread. On slower phones you may hear clicks with big patches.
- Patches are saved on your device; nothing is sent to a server.
- Third-party plugin downloads and online patch libraries are turned off in this build.
Source code
The complete corresponding source is published right here, with no account needed. That covers the build scripts, our changes, every licence file and a written offer. Go to the source downloads →