Don't think there's any other profession like programming that has created such a vibrant ecosystem of free resources for learning

https://the-collab-lab.codes/
https://www.frontendmentor.io/
https://www.chingu.io/
https://www.outreachy.org/
https://www.freecodecamp.org/
https://teachyourselfcs.com
https://csprimer.com/
http://project-awesome.org
http://nand2tetris.org
http://github.com/ossu/computer-science
http://natureofcode.com
http://thecodingtrain.com
http://gitcode.net/m0_47670683/free-programming-books/-/blob/master/books/free-programming-books.md
http://nickm.com/ep2e/
https://aesthetic-programming.net