What are some powerful open source projects everyone should know?

The goal of this post is to provide a hub to discover some powerful internet resources out there.

For example here's one I wanted to share.

• Open Source Ecology is a project for open source hardware that is significantly cheaper than retail costs. Some of the equipment include open source designs for CNC machines, windmills, tractors, plasma cutters, power supplies, motors, generators, and much more!

https://www.opensourceecology.org/

Additional Resources

• The List of Awesome: https://github.com/topics/awesome
• Library Genesis: https://en.wikipedia.org/wiki/Library_Genesis