Midi Writer Js
Web Audio Api
The Web Audio API, developed by the W3C Audio WG
alphaTab is a cross platform music notation and guitar tablature rendering library.
Media Tags Reader (ID3, MP4, FLAC)
An audio effects library for Web Audio, made by www.dinahmoe.com
Web Audio DAW. Use the HTML5 Web Audio API for dynamic sound synthesis. It's like jQuery for your ears.
The HTML5 Audio Compatibility Layer
Flocking - Creative audio synthesis for the Web
Sound Manager 2
Navigable waveform built on Web Audio and Canvas