OGS is described as 'Learn, train, play, and more for free'. There are more than 10 alternatives to OGS, not only websites but also apps for Windows, Linux, Mac and iPhone. The best alternative is qGo, which is both free and Open Source. Other great sites and apps similar to OGS are KaTrain (Free, Open Source), GNU Go (Free, Open Source), ccGo (Free, Open Source) and Goban.co (Free).
• Review your games to find the moves that were most costly in terms of points lost. • Play against AI and get immediate feedback on mistakes with option to retry. • Play against a wide range of weakened versions of AI with various styles.
GNU Go is a 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.
Share your Go board link with a friend and start playing! Goban gives you a Go board to use however you want. Play a game with a friend, analyze a position or simply play around with it to your heart's content.
JagoClient is an - a SGF (Smart Go Format) and XML go game viewer to edit and store Go games, - an IGS client to play on any IGS compatible Go server, - a point to point go player to play against other players without any server, - a GMP (Go Modem Protocol) client to play...
SmartGo for Windows is the complete tool for Go players, with a database of more than 45,000 professional games. Compared to other Go programs, SmartGo is more powerful and easier to use. It's a tool to play, record, replay, analyze, annotate, and print Go games.