ChessDB - ChessDB - a free Chess database for Mac OS X, Windows, Linux, and UNIX - like ChessBase, but better
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.
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.
Lichess - The complete chess experience, play and compete in tournaments with friends others around the world.