SuperCollider - A real time audio synthesis engine, and an object-oriented programming language specialised for...
Chataigne - Artist-friendly Modular Machine for Art and Technology
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.
IanniX - IanniX is a graphical open source sequencer, based on Iannis Xenakis works, for digital art.
ChucK - A strongly-timed music programming language
ossia score - Open-source interactive sequencer for the intermedia arts