Ask HN: Open-source projects that do something good for the world?

Hey all. I'm currently unemployed (like many in the current market), and am looking to spend some of my newly found free-time contributing to OSS.

I'm particularly interested in projects that have a net positive impact on the world. Be it environmental, social, or otherwise.

I'm hoping the community here could provide some recommendations. My background is primarily web dev, but don't limit your suggestions to that domain, I'm always happy for an excuse to learn a new language/domain.

Thanks in advance!