Open-source software dominates the internet, and internet chess is no different. It can't be exaggerated how much easier it is for a developer to build something when they don't have to start from scratch, when they can build on the work of others. With that in mind, Lichess wanted to give a helping hand to a few websites that follow our free and open-source software philosophy. Please give them a try!
https://youtu.be/zira4AZJpQ8
Blitz Tactics
Opening Tree
PyChess
lidraughts.org
Our Favorite Open-Source Sites #1