Playing against KataGo

KataGo — one of the strongest open-source Go engines — has an account here and accepts challenges like any other player. Send an invite to the handle katago from Invite, on any board size, with or without handicap.

• Games are unrated. The bot is listed at 9 dan; playing it never moves your rating, and the invite form won't offer a rated game against it.
• It replies on its own. After your move you'll see KataGo is thinking… — the reply usually lands in a few seconds, though the very first move of a quiet day can take a little longer while the engine wakes.
• Undo works in your favour. Against a human you can only withdraw a move before your opponent answers. Against KataGo you may undo after it replies — the undo takes back both its answer and your move, so a slip needn't cost the game.
• It plays handicap games out. KataGo measures its chances against itself, not against you, so at a high handicap it reads its own position as near-hopeless from the opening — while still being very likely to beat a human. It therefore ignores that until a game is most of the way through, and resigns only when it is also well behind on the board. A four-stone game is a real game, not a two-move concession.

When a game ends you can hand it straight to the same engine for analysis — see Reviewing a game with KataGo.