www.codeproject.com/

http://codeforces.com/profile/codeadda

https://codeground.in/landingpage/

https://www.codeplex.com/

http://www.codeproject.com/

http://codepad.org/

https://coderpad.io/

https://www.codecademy.com/

https://code.org/

http://www.c-sharpcorner.com/

http://www.codeguru.com/csharp/