Ask HN: Any nonprofits looking for open source engineering volunteers?

Inspired by the recent post about Open Library (Internet Archive). Sometimes when someone wants to get involved in open source, they are pointed at libraries or tools on Github. But for some people they find more value in contributing to a nonprofit they believe in. Want to share any you volunteer with or know about?

I can start -- Lichess.org is one of the largest chess websites out there, and it is a nonprofit powered by open source software. Anyone interested in Scala can surely find some issues they are interested in.