Lichess book + Stockfish
Not blunders in time trouble — quiet opening moves you repeat every week. Leak Lab reads your games, checks every repeated decision against the book and the engine, and shows you the exact move to change.
Free · runs on your recent games · sign in to keep your progress · see it on a sample archive
Two Knights · after 5.exd5 −1.9 in 14 games
5…Nxd5 — your move, 71% of the time 5…Na5 — the book's answer
One leak, of the kind a report turns up. The knight recapture looks natural and loses just under two pawns of value every time it is played.
You give it a username. It does the reading, the counting and the second-guessing for you.
Pull your recent games by username, or drop in a PGN. Openings get grouped so repeated decisions stand out.
Once against a Lichess-derived opening book, once against a bundled Stockfish. Agreement matters more than either alone.
Each leak becomes a position you play out against the engine until the better move is the one your hand reaches for.
An example report: a club player at 1540, 183 games read. Five leaks account for most of the damage.
move 1move 16
Most of the damage lands between moves 5 and 9 — before either side has finished developing.
Positions you keep reaching with nothing committed. These are the cheapest points on the board to win back.
Stockfish will happily call your move playable. The book knows that at your level, nobody scores with it. Leak Lab only flags a move when both agree something is wrong — the evaluation drifts and the practical results follow it down.
That is why the list is five lines long instead of fifty. Fixing a repeated opening move is worth more than memorising a new one.
5…Nxd5your move
5…Na5book’s answer
Ninety seconds, your username, and a list short enough to actually fix.