Chess Tempo Database - Chess Tempo Database gives you a library of more than 2 million searchable chess games.
Lichess - The complete chess experience, play and compete in tournaments with friends others around the world.
DecodeChess - AI chess tutor and analysis
XBoard - XBoard, also known as WinBoard on Microsoft operating systems, is a free graphical user interface...
Scid vs. PC - Chess database and playing program.
Chess.com - Play chess on Chess.