Draw, discard, claim — build four sets and a pair to win. Chi sequences from your left, Pon triplets from anyone, and call Ron or Tsumo to take the hand. Choose your rules: Hong Kong, Taiwanese 16-tile, or Japanese Riichi. 4 players, peer-to-peer: no accounts, no server, just a room code. Short on players? Add bots.
An online Mahjong table for four, running peer-to-peer over WebRTC. Browsers find each other with Google STUN servers and a free signaling broker, then talk directly. The game lives in the host's tab — keep it open!