GNU Go is described as 'free program that plays the game of Go. GNU Go has played thousands of games on the NNGS Go server. GNU Go is now also playing regularly on the Legend Go Server in Taiwan, on the WING server in Japan, and many volunteers run GNU Go clients on KGS'. There are five alternatives to GNU Go for Linux, Windows, Mac and Online / Web-based. The best alternative is Sabaki, which is both free and Open Source. Other great apps like GNU Go are KaTrain, OGS, Fuego and Kigo.