CheckChess

Something felt wrong about that game. CheckChess tells you whether the feeling holds up.

Paste a username from Chess.com or Lichess and get a 0-100 suspicion score, built from move accuracy, how often the player matches the engine's first choice, average centipawn loss, move-time patterns, and how all of it compares to typical play at their rating.

WHAT IT DOES
• Account scans — any Chess.com or Lichess username, scored from that player's public game history.
• OTB analysis — paste a PGN from a tournament or a club game and get the same treatment.
• Detailed reports — per-move accuracy, centipawn loss and engine-match rate, charted game by game, so you can see where a verdict comes from instead of taking a number on faith.
• Watchlist — keep an eye on accounts and get told when something changes.
• AI analyst (Premium) — ask follow-up questions about any report and get answers grounded in that specific analysis.

THE ENGINE RUNS ON YOUR PHONE
Stockfish works through the games on the device itself. The engine pass never goes to a server, and a PGN you paste never leaves your phone to be evaluated.

IT REFUSES TO GUESS
A verdict on eight moves is worthless, so CheckChess does not give one. Short games, engine-vs-engine games and thin samples are excluded and reported as such. The score compares a player against people of their own strength, not against a grandmaster.

WHAT CHECKCHESS IS NOT
The score is a statistical signal, not proof. It exists to inform your own judgement — not to be used as a public accusation against anyone.

FREE
• 5 account scans and 3 PGN analyses a month
• 1 watched account
• Summary reports

PREMIUM
• Unlimited account scans and PGN analyses
• Full reports: charts, flags, per-move breakdowns
• AI analyst: 30 messages a week on Weekly, 1200 a year on Yearly
• 10 watched accounts
• PRO badge on your profile

Premium is a subscription billed through the App Store or Google Play. Cancel anytime from your store account settings.

CheckChess is not affiliated with or endorsed by Chess.com or Lichess. Stockfish is used under the GNU GPL v3.