When playing on Lichess, you must not:

1. Cheat. We prohibit the use of any external assistance used whilst a game you are involved in is ongoing, which has the effect of improving your knowledge, calculation ability, or otherwise gives you an unfair advantage over your opponent. Examples of cheating include, but are not limited to, using a chess engine, opening books, endgame tablebases, receiving move recommendations from another person or software (including human commenters on streaming or social media services), and certain software or extensions at our discretion. In correspondence games only, you may use the Lichess opening explorer, plus any other chess books or opening databases.

2. Use play extensions. We prohibit the use of any program or browser extension that assists with playing moves. The only legal ways to play moves on Lichess are with the official Lichess APIs for Boards and Bots, or by interacting directly with the official Lichess graphical user interface (GUI). Programmatic usage of the GUI for playing moves is forbidden. However, custom styles and graphical tweaks of the play interface are allowed, using CSS.

Rules grid

Playing on the website or with the mobile app

Playing with a third party client and/or the Lichess API