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JSONLoops is a multi-user audio sequencer reminiscent of Fruityloops. Audio playback is handled by node.js servers, while multiple browsers act as control devices. Songs are stored in the JSONloop format, which are simply nested JSON arrays.


This is Alpha software which was created for NYC Music Hack Day 2011. We won best collaborative project. This library works and is awesome. It could be epic if we all work on it.


We are currently trying to raise money to make JSONloops a "real" project, instead of just a proof of concept. Please visit: to read more.

Video Demo

Warning: The current installation process for JSONloops is not complete. We were in a rush to make a working prototype and we haven't bundled all the deps correctly into a NPM package. We'll have a NPM package published shortly.

Installation (coming soon)

npm install JSONloops

Now you will have to rebuild node as 32bit, since irrKlang doesn't support 64 arch's yet.

cd /path/to/node ./configure --dest-cpu=ia32 make make install

We'll be replacing this last step with a much easier process soon.


To get started, you'll want to clone the JSONloops project and use the demo server

git clone
cd jsonloops
node server.js

The audio sequencer will now start playing on your local machine, you'll hear sounds. To access a control interface for your JSONloops server, visit http://localhost:8080/

Why did you build this?

Because I'm insane.

The JSONLoop format

A JSONLoop is nothing but a nested JSON array that follows a somewhat specific format.

the arrays are nested in the following hierarchy 

*       BEATS

Check out the nyc.json file or metronome.json file for example loops.

can anyone create a proper json-schema to represent this? it also has to validate the loop is well formed...


Marak Squires - Created project, JavaScript, HTML, CSS, invented the JSONloops format, built core sequencing code

Elijah Insua - Writer of C bindings, solver of the hard problems

hij1nx - Writer of C bindings, JavaScript, HTML, CSS UX and UI.