Pure Data

Pd (aka Pure Data) is a real-time graphical programming environment for audio, video, and graphical processing. It is the third major branch of the family of patcher programming languages known as Max (Max/FTS, ISPW Max, Max/MSP, jMax, etc.

Free Open Source Mac OS X Windows Linux

OpenFrameworks

openFrameworks is an open source C++ toolkit designed to assist the creative process by providing a simple and intuitive framework for experimentation.

Free Open Source Mac OS X Windows Linux

Csound

Csound is a sound design, music synthesis and signal processing system, providing facilities for composition and performance over a wide range of platforms.

Free Open Source Mac OS X Windows Linux