The Software Freedom Conservancy helps Free/Open Source software projects by providing infrastructure, financial structures, and legal help. It is a not-for-profit organisation that is dedicated to software freedom, something that I think is an important prerequisite for a decent world in the future.
Conservancy looks after lots of projects, including these ones that I personally use: Boost, BusyBox, Etherpad, Git, Godot Engine, Inkscape, phpMyAdmin, QEMU, Racket, Samba, Selenium, Squeak and Wine.
It provides an easy way for projects to accept donations, hold assets and negotiate contracts, as well as mentoring and legal advice. It also leads the difficult and thankless work to persuade (and force) companies to comply with the GPL (a Free Software license). Without this work a great deal more Free Software would be distributed without the required access to source code, meaning it is not free at all.
Further, it is a key supporter of Outreachy, which does important work to address the under-representation, systemic bias, and discrimination in the technology industry.