I’ve been using and following projects like MIT OCW to supplement my coursework since high school but I really started to hoard these links like a dragon during the pandemic lockdowns. My own institution had been struggling with the transition to online and I found myself both in need of additional study material and with a whole lot more time on my hands. So with the intent of gradually working through the courses over my adult life I started going through the various institutional websites and cataloging the ones that interested me. All that said, I’ve always been primarily interested in projects like OCW because I believe that democratizing knowledge is the most important thing the internet does. As far as finding more courses, I’ve found that if you watch a few of them the youtube algorithm will eventually reveal that there is an absolute mountain of this sort of content on that platform. There’s also the institution websites themselves (see MIT and Yale). I tend to preference courses that are book based rather than have a lot of custom content as those are always easier to find.