Pure Data

Having left Max to its commercial publishers, Miller Puckette started over at UC San Diego in 1996. The result, Pd, shares the core idea — a patch window where objects are wired together and audio objects end in a tilde — but is open source under a BSD licence and saves patches as readable text. Puckette has described the spartan look as deliberate, and few have talked him out of it.

Its strength is that the engine can be lifted out. The libpd library lets a patch run as the audio engine of a mobile app or a game with no user interface at all. Pd speaks MIDI and OSC and is a fixture in installation art and Raspberry Pi-based instruments.