Wavesurfer.js
Navigable waveform built on Web Audio and Canvas
Teoria
A JavaScript music theory framework.
Vexflow
A JavaScript library for rendering music notation and guitar tablature.
Midi Writer Js
♬ JavaScript library providing an API for programmatically generating expressive multi-track MIDI files in browser and Node.
Speak.js
Text-to-Speech in JavaScript using eSpeak
Howler.js
Javascript audio library for the modern web.
Jsmediatags
Media Tags Reader (ID3, MP4, FLAC)
Tuna
An audio effects library for Web Audio, made by www.dinahmoe.com
Webaudio.js
web audio library for games
Buzz
Buzz is a small but powerful Javascript library that allows you to easily take advantage of the new HTML5 audio element. It tries to degrade gracefully on non-modern browsers.
Pizzicato
Library to simplify the way you create and manipulate sounds with the Web Audio API.
Sound JS
A Javascript library for working with Audio. Features a simple interface as the front end to multiple audio APIs via a plugin model. Currently supports HTML5 Audio & Flash.
Sound Manager 2
A JavaScript Sound API supporting MP3, MPEG4 and HTML5 audio + (experimental) RTMP, providing reliable cross-browser/platform audio control in as little as 10 KB. BSD licensed.
Midi.js
Making life easy to create a MIDI-app on the web. Includes a library to program synesthesia into your app for memory recognition or for creating trippy effects. Convert soundfonts for Guitar, Bass, Drums, ect. into code that can be read by the browser. Supports multiple simultaneous instruments and perfect timing.
Flocking
Flocking - Creative audio synthesis for the Web
Timbre.js
JavaScript library for objective sound programming
Pedalboard.js
Open source JavaScript framework for developing audio effects for guitars using the Web Audio API.