LeetCode
leetcode description
all allResources
CS50
Harvard University's introduction to the intellectual enterprises of computer science and the art of programming.
beginner all 
Dave Leeds
Dave Leeds description
intermediate kotlin 
Stack Overflow
Stack Overflow description
all all 
Victor Gordan
Opengl stuff
advanced C++ 
Sebastian Lague
Procedural C# and unity stuff like terrain and planet generation
intermediate C#