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JZZ: MIDI library for Node.js and web-browsers

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JZZ.js allows sending, receiving and playing MIDI messages in Node.js and all major browsers in Linux, MacOS and Windows. Some features are available on iOS and Android devices.

JZZ.js enables Web MIDI API in Node.js and those browsers that don't support it, and provides additional functionality to make developer's life easier.

For the best user experience, it's highly RECOMMENDED (though not required) to install the latest version of Jazz-Plugin and browser extensions from Chrome Web Store or Mozilla Add-ons.


  • MIDI In/Out
  • User-defined MIDI nodes
  • MIDI files
  • MPE
  • Additional modules


npm install jzz --save
or bower install jzz
or yarn add jzz
or get the full development version and minified scripts from Github

Note: in the (unlikely) case you get into trouble installing the midi-test module, that requires special system configuration, you can safely remove it from the devDependencies by running npm remove midi-test --save-dev.


Plain HTML
<script src="JZZ.js"></script>
<script src=""></script>       // the latest version, or
<script src=""></script> // any particular version
CommonJS (Browserify and Node.js command line applications)
var JZZ = require('jzz');
require(['JZZ'], function(JZZ) {


(Node.js example)
var navigator = require('jzz');
navigator.requestMIDIAccess().then(onSuccess, onFail);
// ...
navigator.close(); // This will close MIDI inputs,
                   // otherwise Node.js will wait for MIDI input forever.
// In browsers the funcion is neither defined nor required.


MIDI Output/Input
JZZ().or('Cannot start MIDI engine!')
     .openMidiOut().or('Cannot open MIDI Out port!')
     .wait(500).send([0x90,60,127]) // note on
     .wait(500).send([0x80,60,0]);  // note off
JZZ().openMidiIn().or('Cannot open MIDI In port!')
     .and(function() { console.log('MIDI-In: ',; })
     .connect(function(msg) { console.log(msg.toString()); })
Connecting MIDI nodes
var input = JZZ().openMidiIn();
var output = JZZ().openMidiOut();
var delay = JZZ.Widget({ _receive: function(msg) { this.wait(500).emit(msg); }});
Helpers and shortcuts
// All calls below will do the same job:
port.send([0x90, 61, 127]).wait(500).send([0x80, 61, 0]);   // arrays
port.send(0x90, 61, 127).wait(500).send(0x80, 61, 0);       // comma-separated
port.send(0x90, 'C#5', 127).wait(500).send(0x80, 'Db5', 0); // note names
port.noteOn(0, 'C#5', 127).wait(500).noteOff(0, 'B##4');    // helper functions
port.note(0, 'C#5', 127, 500);                              // another shortcut'C#5').wait(500).noteOff('C#5');          // using channels'C#5', 127, 500);                           // using channels

Additional modules

  • JZZ-midi-SMF - Standard MIDI files: read / write / play
  • JZZ-midi-GM - General MIDI instrument names: MIDI to string / string to MIDI
  • JZZ-midi-Gear - Retrieve your MIDI device model and manufacturer
  • JZZ-input-Kbd - Virtual piano controls for your MIDI projects
  • JZZ-synth-OSC - A simple Web Audio synth to use when MIDI is not available
  • etc... - Import third-party solutions into the JZZ framework

Check the Getting Started page and the API reference for more information.
Your questions and comments are welcome here.

We would really appreciate your support!