ECTool: a very popular tool supported on all versions of Windows from XP to Windows 8.1. Freeware.
Scid: a popular chess database application for Unix/Linux and Windows operating systems. Free.
Winboard: a graphical user interface for chess games. Supported on all versions of Windows from XP to Windows 8.1. Free.
ChessPad: a chess database program with many features. Requires Windows XP or higher. Freeware.
Bookup: a tool for learning chess openings. Free trial.
Chessbase 13: a personal stand-alone chess database with many advanced features. Reccomends Windows 7 or higher (64bit). Commercial.
Chess Rating Calculator: a tool to calculate your rating; easy to use.IECC Chess Rating Calculator: a tool for rating IECC games written by Brad Coulding. Macintosh
ExaChess: a database program. Freeware version avaliable.
Sigma Chess: a free chess-playing program and database with many features.
ChessPuzzle 2: an easy to use puzzle solving game, with over 6000 puzzles and a powerful built-in chess engine.