An audio effects library for the Web Audio API.
Check the wiki: https://github.com/Theodeus/tuna/wiki
Or a live example: http://codepen.io/Theodeus/pen/oxKjmy?editors=0010
This is a very incomplete list of places where Tuna.js is used.
http://www.jamwithchrome.com/ - Jam With Chrome allows you to jam online with your mates across the globe using an assortment of instruments and effects. There's even a mode for dummies!
https://github.com/selfrefactor/tuna-player - A React.js/Electron wrapper around Tuna.js!
https://slasher.chillertv.com/ - interactive experience for the TV show Slasher
http://looplabs.com/beta - Looplabs is a collaborative cloud based music studio that lets anyone, regardless of technical skills or ability, quickly and easily make professional quality music anywhere, anytime and with anyone.
http://www.websynths.com/ - Browser-based microtonal midi instrument
https://www.npmjs.com/package/react-music - Make music with React!
http://bapjs.org/ - Beat making toolkit