LearnChess 
LearnChess is a open source project made to help people get better at chess.
Features
Puzzles
You can submit puzzles and get a rating by solving. All puzzles are made by people and reviewed by people. This helps make them more natural and educational. Chessvariants is similar except it is for chess variants only.
Coordinates trainer
Lichess and Chess.com have it, so LearnChess needs it too. You can optionally display your latest score on your profile.
Play with the computer
Play against the JavaScript version of Stockfish 8. Features like takebacks and different levels are coming soon.
Credits
See the thanks page.