Lichess (/ˈliːtʃɛs/; LEE-ches)[3][4] is a free and open-source Internet chess server run by a non-profit organization of the same name.

Lichess is ad-free and all the features are available for free, as the site is funded by donations from patrons, who receive a special badge as thanks for their support.

[14] In April 2021, the United States Chess Federation announced its official endorsement of Lichess's fair play methodology that automatically detects cheaters based on engine move matching analysis.

[23] Other participants in past editions include Fabiano Caruana, Maxime Vachier-Lagrave, Vladimir Fedoseev, Vladislav Artemiev, Alexander Grischuk, and Anish Giri.

In May 2020, the SLCC hosted the Clutch Chess: USA on Lichess, a four-player knock-out event with $100,000 in prizes.

[26] The participants were Magnus Carlsen, Maxime Vachier-Lagrave, Leinier Domínguez, Alexander Grischuk, Levon Aronian, Fabiano Caruana, Wesley So, and Jeffery Xiong.

The article included previously unpublished details of sexual misconduct allegations against two US grandmasters, and criticized the handling of it by both organizations.

[36][37] In May 2020, Lichess hosted the Play for Russia charity event, to raise money for hospitals and health workers fighting the COVID-19 pandemic.

In the same month, several chess players (including Sebastien Feller) hosted a charity event on Lichess to raise money for the Mercy hospital in Metz, France, in the fight against COVID-19.

[42] In August 2020, the Qatar Chess Federation hosted the Katara International Bullet Tournament on Lichess, with a prize fund of $10,000.

[44] The 2021 edition with a prize fund of $12,800 was won by Vladislav Artemiev; in the finals, he beat Andrew Tang, who had knocked out Magnus Carlsen in the semifinals.

The 4545 Lichess League aims to promote competitive play and community engagement among chess enthusiasts worldwide.

[46][47] The website allows users to play games of live and correspondence chess against other players at different time controls.