Vexflow
A JavaScript library for rendering music notation and guitar tablature.
Wavesurfer.js
Navigable waveform built on Web Audio and Canvas
Web Audio Api
The Web Audio API, developed by the W3C Audio WG
Tuna
An audio effects library for Web Audio, made by www.dinahmoe.com
Pedalboard.js
Open source JavaScript framework for developing audio effects for guitars using the Web Audio API.
Jsmediatags
Media Tags Reader (ID3, MP4, FLAC)
Mp3.js
A JavaScript MP3 decoder for Aurora.js
Audio.js
A cross-browser javascript wrapper for the html5 audio tag
Flac.js
FLAC decoder in JavaScript
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.
Wad
Web Audio DAW. Use the HTML5 Web Audio API for dynamic sound synthesis. It's like jQuery for your ears.
Webaudio.js
web audio library for games
Audiolet
A JavaScript library for real-time audio synthesis and composition from within the browser
Amplitudejs
A Javascript library that allows you to control the design of your media controls in your webpage -- not the browser. No dependencies (jQuery not required)
Midi Writer Js
♬ JavaScript library providing an API for programmatically generating expressive multi-track MIDI files in browser and Node.
Waud
Web Audio Library
Timbre.js
JavaScript library for objective sound programming