W3Schools is a popular web site for learning web technologies online.

PythonAnywhere is an online Integrated Development Environment (IDE) and Web hosting service based on the Python programming language.

CodeHS is an interactive online learning platform offering computer science and programming instruction.

CodeCloud.me is a platform for learning programming.

Tutorialspoint provides free tutorials online.

repl.it is a cloud coding environment.

Codility.com is a platform to hire developers and other resources.

Collabedit is an online code editor that lets people collaborate in real-time.