2 years ago we released a public API for Bots, that allows chess engine developers to test their creations against players and other bots.

While the Bot API can also be used by human players, it is restricted to challenge games, and require creating a special BOT account. As a result, it has been mostly used for creating artificial opponents.

Enters the new Board API. Designed for devices that are operated by a single human player, it has a different set of capabilities and restrictions that makes it more suitable to electronic boards and third-party clients. It can be used with a normal Lichess account, and it can play pool games and tournament games.

Here's a comparison of the Board API and the Bot API.

Board API

For e-boards and any chess client operated by a single human player.

Features

• Play games, read/write chat, create/receive challenges
• Compatible with normal Lichess accounts
• Lobby games, tournament games, challenges and AI games

Restrictions

• Time controls: Rapid, Classical and Correspondence only. For direct challenges and games vs AI, Blitz is also possible.
• Engine assistance is strictly forbidden

Links

• API documentation
• Certabo client
• Supported clients will be added here as they are implemented!

Bot API

For chess engines, centaur/cyborg play, and vote chess programs.

Features

• Play games, read/write chat, create/receive challenges
• Engine assistance is allowed
• All time controls are allowed, with the exception of UltraBullet

Restrictions

• Requires a special BOT account
• Only challenge games and AI games. Pools and tournaments are off-limits.
• Rated games only grant half the points
• No leaderboards

Links

• API documentation
• Open-source support for Certabo boards
• Liboard DIY electronic chessboard using photoresistors
• Speak to Lichess
• An Arduino electronic chessboard
• OpenChessBoard, an open-source smart chess board to play online chess on a physical chess board
• light lc, a minimalistic play app
• cli-chess A highly customizable way to play chess in your terminal.

If you develop a chess client based on the new Board API, please let us know, and we will list it here.

Happy coding and chessing!

Illustrations: ChessboARDunio by @bichopebitou

F.A.Q.

• Why is it restricted to Rapid, Classical and Correspondence?
  For cheating reasons. When moves are received through an API, Lichess can't tell who really played them. Is could be a person, or a chess engine. The Lichess website and mobile app embed cheat detection tools that help us know if moves are played fairly. But APIs bypass these tools.
  Of course, most of our cheat detection happens on the server-side, and therefore also applies to the Board API. But we still don't feel comfortable giving up on client-side detection for any games faster than Rapid.