About OpenMahjong

OpenMahjong exists for one reason: mahjong is wonderful, confusing and badly documented in English. Great information is scattered across forums, paywalled apps and rulebooks from the 1920s. We collect and rewrite it — clearly, accurately and for free.

The site covers six major variants (riichi, Hong Kong, American, Taiwanese, Sichuan, Chinese Classical), every tile in the standard set, and the vocabulary that real tables use. It is built to be read in one sitting and used at your next game.

How it's funded

The site is free forever, with no signup and no paywall. Operating costs are covered by unobtrusive display advertising. We never sell personal data, and ads never gate content. If an ad is ever annoying, that's a bug — tell us at hello@openmahjong.net.

Editorial standards

Rules content is cross-checked against official and community sources for each variant, and pages carry a visible "last updated" note where rules vary by house. When regional rules genuinely differ, we say so instead of pretending one answer exists.

Contact

Corrections, requests and (polite) rants about house rules are welcome: hello@openmahjong.net