XBoard

XBoard is a graphical user interface for chess in all its major forms, including international chess, xiangqi (Chinese chess), shogi (Japanese chess) and Makruk, in addition to many minor variants such as Losers Chess, Crazyhouse, Chess960 and Capablanca Chess. It displays a chessboard on the screen, accepts moves made with the mouse, and loads and saves games in Portable Game Notation (PGN). It serves as a front-end for many different chess services, including:

• Chess engines that will run on your machine and play a game against you or help you analyze, such as GNU Chess, Crafty, or many others.
• Manage tournaments for chess engines, where you can play your engines against each other.
• Chess servers on the Internet, where you can connect to play chess with people from all over the world, watch other users play, or just hang out and chat.

Notes: The OS X bundle includes demo engines fairymax and fruit, as well as elephant eye, hakikid, shogkidoki, gnu shogi, and hachu for playing variants. Also on top of its own native CECP (aka xboard) protocol, XBoard.app also supports UCI, UCCI, and USI protocols through the built-in polyglot and UCI2WB adapters. It also includes scripts for launching XBoard with the FICS and ICS chess servers.