https://medium.com/free-stuff/500-free-things-on-the-internet-to-start-your-new-year-11ae72266b66

http://libgen.is/ has all kinds of academic resources (books, articles, images, audiobooks, etc) that are normally paywalled

https://www.youtube.com/@cs50 has harvards famous CS50 (Harvard University’s introduction course to computer science) which is really cool.

If you’re in the US: your local library. There’s a very good chance they have huge amounts of resources available for anyone with a library card. And if you don’t already have a library card, get one ASAP!