- Open Textbook Library - https://open.umn.edu/opentextbooks/
- Thinkster - https://thinkster.io/
- https://www.codecademy.com/
- https://egghead.io/
- Frontend Masters - https://frontendmasters.com/
- https://instruqt.com/ - The Next Generation Hands-on Virtual IT Labs for Software Adoption
- Scrimba - https://scrimba.com/
- LeetCode - https://leetcode.com/
- Replit - https://replit.com/
- CodeCrafters - https://app.codecrafters.io/
- Codewars - https://www.codewars.com/
- CodinGame - https://www.codingame.com/home
- Robocode - https://robocode.sourceforge.io/
- Gladiabots - AI Combat Arena - https://gladiabots.com/
- VIM Adventures - https://vim-adventures.com/
- SoloLearn - https://www.sololearn.com/
- Sphere Online Judge (SPOJ) - https://www.spoj.com/
- CodeGym - https://codegym.cc
- Kode Kloud - https://kodekloud.com/
- Factorio - https://www.factorio.com/
- KataCoda - https://www.katacoda.com/