Pure Data (pd)

Pure Data (Pd) is a visual programming language developed in the 1990s for creating interactive computer music and multimedia. It has a very basic user interface, but is quite powerful and popular for synthesis and electronic music.

https://puredata.info/

See also:

• http://cuinjune-purr-data.glitch.me/ Pure Data in the web browser. No install needed.
• https://z.musictools.live/ A synthesizer visual programming language in a browser window. Inspired by Pure Data and others