Chess Companion

Analyse any chess position with a built-in Stockfish engine: best move, eval bar and a live board on chess.com and Lichess.

Understand every position. Chess Companion opens in your browser's side panel and analyses the position on the board you have open . It uses Stockfish, one of the strongest chess engines in the world, running entirely on your own computer. Why install it See the best move, in plain notation. Moves appear as you'd read them in a book (Nf3, Bxc6, O-O), not as coordinates like g1f3. Know who's winning at a glance. An evaluation number and a bar show who's ahead, with a short summary: "White is better", "Roughly equal" and so on. Follow along on a clean board. The panel keeps its own copy of the position, with an arrow on the engine's best move. It flips automatically so your side stays at the bottom. Learn from your own games. Review a finished game, spot where it went wrong, and see what the engine would have played. Private and light The engine runs locally. Nothing about your games is sent anywhere, and no data is collected. It only reads the board on chess.com and lichess.org, and never changes the page. No account, no ads, free to use. Made for study Chess Companion is a learning and analysis tool. Don't use it to get help in games against other players. That breaks the fair-play rules of chess.com and Lichess and can get your account closed. Open source (GPLv3). Not affiliated with chess.com or Lichess. Like it? You can support the project with a coffee on Ko-fi.