ChessLab

ChessLab is a complete chess companion for iPhone and iPad: play, analyze, train and experiment, with the Stockfish engine built in and without ever leaving the app.

HUMAN OPPONENTS
Nine characters played by Maia-3, a network trained on millions of human games: it does not look for the best move, it plays the one a human of that level would play, blunders included. Each has a style, a repertoire, a temperament, a portrait, and an adjustable level on the human scale. Or take on Stockfish itself, from beginner (~900 Elo) to maximum (~3190 Elo). With or without a clock. Hints, a warning before risky moves, and an evaluation bar can all be toggled on demand.

TWO PLAYERS
Play locally on the same device, with a "pass-and-play" mode that flips the pieces so both players read the board comfortably.

ANALYZE
Run a game or a position through Stockfish: move-by-move classification (inaccuracy, mistake, blunder, brilliant move…), an evaluation graph, best-move and opponent-threat arrows, and auto-play through the moves. Import by PGN, FEN, position editor, or photo scanner.

OPENINGS
Pick an opening and step through it move by move: every move is explained, the alternatives are offered, and colored arrows link the board to the move list. 58 hand-written openings (bilingual), all reviewed by the engine, with simplified spaced-repetition training to memorize them.

THE ENDGAME CORNER
78 courses proven by endgame tablebases — the exact mathematical verdict: no taught move gives up a win, no recommended defence loses a draw. Nine families, from the opposition to famous studies. And free training: finish the position against best defence, where any move that preserves the verdict is accepted — not just the lesson's move.

VARIANTS
Chess960 (Fischer Random Chess): a randomly drawn starting position, one chosen by number, or one you compose yourself, with a full post-game analysis just like "Play" mode. Eleven more variants against the computer, each with its own analysis: King of the Hill, Three-Check, Horde, Racing Kings, Atomic, Antichess, Crazyhouse, Stolen Move (a token every 7 moves lets you play twice in a row), Duck Chess, Barricades and Random Barricades.

YOUR OWN REPERTOIRES
Import your openings as PGN, variations included, and drill them with the same system. Share a repertoire as a single file — no account, no server. What you already know about a position counts right away in the imported repertoire.

PUZZLES
Over 100,000 tactics puzzles from the Lichess database, filterable by rating and theme, plus puzzles generated automatically from your own mistakes in analysis. Spaced repetition and progress tracking included.

LABORATORY
Pit two Stockfish configurations against each other over a series of games to compare their strength, with an estimated Elo gap and confidence interval.

EDITOR AND SCANNER
Set up a position by hand, or scan it from a screenshot or a photo — review and correct the recognized position before playing or analyzing it.

BUILT FOR IPAD
Full-size board with move list, graph and MultiPV visible at once, keyboard and trackpad support, polished portrait and landscape layouts.

iCLOUD SYNC (optional)
Turn on iCloud sync in Settings so your games follow you across all your devices, via your private iCloud. No account to create, no ChessLab server. Off by default: the app works fully offline.

PRIVACY
Offline by default: no ChessLab server, no analytics, no ads. Your games and settings stay on your device. iCloud sync, if you enable it, uses your own private iCloud — your data is never shared with the developer. Fully bilingual, French and English.

ChessLab embeds the Stockfish engine (GPLv3 license), the University of Toronto's Maia-3 network (AGPLv3 license) and free vector piece sets — cburnett (GPLv2+/CC BY-SA), chessnut (Apache 2.0) and merida (GPLv2+). Full source code and license notices are available from within the app (Settings → Licenses).