General Comp Sci Topics
- Open Source Society University - a very thorough (intro core and advanced topics) and completely online Computer Science curriculum.
- Programming Historian - the lessons section is an excellent resource
C/C++
- Rosettacode.org - how to accomplish the same task using different languages
- GeeksforGeeks - another repository of algorithms
- Cpluplus - C++ library reference cstdlib for example
- Cpp.sh - online tool for running cpp code
- Glot.io - another online tool for running code in different languages
Java
Python
- Learn Python
- Talk Python To Me Podcast - great way to catch up on what is happening in the Python world from practicioners