SuperCollider - A real time audio synthesis engine, and an object-oriented programming language specialised for...
Pure Data - Pd (aka Pure Data) is a real-time graphical programming environment for audio, video, and graphical...
Sonic Pi - Sonic Pi is a new kind of instrument for a new generation of musicians. It is simple to learn, powerful enough for live performances and free to download.
VCV Rack - A cross-platform modular synthesizer.
ChucK - A strongly-timed music programming language
Synthesine - Live coding environment for experimenting with sound synthesis in the browser.