Lichess

Lichess is an internet chess server that is free and open-source, run by a non-profit organization of the same name. Users of the site may play anonymously or register an account to play games to earn a rating on Lichess. 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. Its features include chess puzzles, computer analysis, tournaments and chess variants.