Band.js : An interface for the Web Audio API that supports rhythms, multiple instruments, repeating sections, and complex time signatures.
Glicol : make music with code. connect different nodes like a synth, sequencer or sampler.
Soundgrain : Soundgrain is a graphical interface where users can draw and edit trajectories to control granular sound synthesis. Soundgrain is written with Python/...
VSTPLANET : VST Plugins Free - Virtual instruments and effects
librosa : librosa is a python package for music and audio analysis. It provides the building blocks necessary to create music information retrieval systems.
ixi audio is an experimental project concerned with the creation of digital musical instruments and environments for generative music.