librosa : librosa is a python package for music and audio analysis. It provides the building blocks necessary to create music information retrieval systems.
ixi software : ixi audio is an experimental project concerned with the creation of digital musical instruments and environments for generative music.
sfxr : A tool to quickly generate 8bit/16 bit-soud effects!
Paul's Extreme Sound Stretch : This is a program for stretching the audio. It is suitable only for extreme sound stretching of the audio (like 50x) and for applying special effects ...
Soundgrain : Soundgrain is a graphical interface where users can draw and edit trajectories to control granular sound synthesis. Soundgrain is written with Python/...
VST Plugins Free - Virtual instruments and effects