Chess Tempo Database - Chess Tempo Database gives you a library of more than 2 million searchable chess games.
DecodeChess - AI chess tutor and analysis
Scid vs. PC - Chess database and playing program.
Lichess - The complete chess experience, play and compete in tournaments with friends others around the world.
Chess Insight - Chess Insight is a chess tutor that helps you with a number of analytical powers for judging every move in chess.
Scid on the go - Scid on the go app allows you to browse Scid (Shane’s Chess Information Database) files and is optimized for databases with millions of chess games.