• Awesome Electronics: https://github.com/kitspace/awesome-electronics
• Open-source Electrical Engineering Curriculum: https://github.com/Artoriuz/OSEE
• Rossmann Repair Training Guide (Louis Rossmann is autistic, btw): https://docs.google.com/presentation/d/1PkeO_lC5WTPScSV3ZzEEjVuDWeQtL2eHK6jEcf7axA0/htmlpresent
• Open Source Society University: https://github.com/ossu
• The Engineering Toolbox: https://www.engineeringtoolbox.com/
• HyperPhysics: http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
• Awesome Math: https://github.com/rossant/awesome-math
• Learn Anything: https://github.com/learn-anything
• MIT OpenCourseWare: https://ocw.mit.edu/
• Free Harvard Online Courses: https://pll.harvard.edu/catalog/free
• Open Yale Courses: https://oyc.yale.edu/
• Library Genesis is your friend if you want to sail the seven seas for textbooks. I typically look up recommended books for different subjects from forum q&a’s on the internet, including reddit and stackexchange, and then I set sail to the good ol’ libgen.
• Archive.org for books and media as well

If you search online for awesome {insert subject here} git (or github), you will find many curated lists of resources. For example: Awesome Mechanical Engineering Resources and Awesome Biology