The ChessBase Online Database is a free, web-based game reference tool providing access to millions of games from professional and top-amateur competitions. It is one of the most comprehensive collections available online, regularly updated with games from major events.

The search interface lets you filter by player name, ELO range, ECO opening code, year, event, and result. The opening explorer view shows statistics — win/draw/loss percentages and average ratings — for any position reached on the board, making it a go-to tool for opening research. Each game can be played through in a built-in viewer.

The online database is free to use without registration. It is a subset of the full ChessBase desktop software's Mega Database, which contains a vastly larger collection with annotations and is a paid product aimed at serious players and professionals.