One that you use, and are therefore both knowledgeable of its use cases and invested in improving.

MediaManager is a relatively new project for downloading movies and tv shows that seems very promising but could probably use some help. It’s a web app written in Python and Svelte and uses the FastAPI framework. They also have a developer guide.

If your nickname is anything to go by, you might be interested in what Blender is currently doing : a lot of work on physics simulations. Recent developments include an xpbd solver for hair and cloth sim, and they’re now looking at implementing a flip solver for fluids.

This is a vast project with more governance and rules than most though, I reckon. I’m not a developer myself but this is the impression I get. Getting involved is probably… involved

Mine. I’m the only one working on it. Please save me.