Essentia : Open-source library and tools for audio and music analysis, description and synthesis
howler.js : howler.js is an audio library for the modern web. It defaults to Web Audio API and falls back to HTML5 Audio.
Overtone : Overtone is an open source audio environment designed to explore new musical ideas from synthesis and sampling to instrument building, live-coding and...
FoxDot : FoxDot is an easy-to-use Python library that creates an interactive programming environment and talks to the powerful sound synthesis engine, called S...
jsmad : jsmad is a pure javascript MP3 decoder, based on libmad, with an ID3 decoder written from scratch.
The Synthesis ToolKit in C++ (STK) is a set of open source audio signal processing and algorithmic synthesis classes written in the C++ programming language.