Pick your handles, your time controls and how far into the game to look. Stockfish replays the opening of every game that matches, in your browser, and reports where you stood at the checkpoint, how those games finished, and which of your own moves cost the most getting there.
Free Runs in your browser · Chess.com and Lichess
The check lives in the My Games tab of Opening Lab, under the same filters as everything else there. Whichever handles, colours and time controls are selected are the games it reviews — and it says so on the report, so a number can always be traced back to a set of games.
Every figure names its own denominator, because "your opening accuracy is 87%" is not something a player can act on and "thirteen of fifty games reached move ten worse, and you scored 27% from them" is.
Pick the move number — eight, ten, twelve or fifteen. Every game is placed by its evaluation there, from your side, and the games are banded: better, level, worse, difficult. It is a checkpoint you chose, not a claim about where your opening ends.
Your game score from the games that reached the checkpoint worse, beside your score from the ones that did not. Both carry the number of games behind them, and neither is described as the cause of the other.
Only your own moves are judged — an opponent’s mistake is not a fact about your preparation. Each one shows the evaluation before and after, the move Stockfish wanted, and what it cost in points of expected result.
The same move from the same position across several games, with what it cost each time and what you scored from those games. A bad move played once is bad luck; the repeated one is the one certain to come up again.
Openings are grouped with the colour you had, because the Sicilian you play as Black and the one you meet as White are different openings that share a name. They are ordered by how many games started badly — not by how bad the single worst one was.
A report you cannot act on is a report you read once. Every row of this one opens on the board, with the engine and both opening databases already answering about that position.
The board goes to the position as you faced it — one move before the mistake, the right way up — and asks for your move. Nothing is revealed until you ask for it.
Show the move you played, or the one the engine wanted, and read the difference. One move can be re-searched on its own at a depth no survey of several hundred positions could afford.
Save what you chose as a preparation. It joins spaced-repetition practice and can be sparred against, so the fix is rehearsed rather than noted.
It does not tell you that your opening lost you those games. What it measures is where a game stood at one move number and how that game finished — and those two things being related is not evidence that one caused the other. An early tactic, the strength of the opponent, the clock and the next thirty moves are all still candidates, and none of them is visible from here.
So the report reports. It says how many games reached the checkpoint worse and what you scored from them, and then it points at specific moves you can check yourself on a board. Deciding whether the repertoire is the problem is your call, and the evidence for it is on the page rather than compressed into a verdict.
The evaluations behind it are a survey depth, picked so several hundred positions fit into a few minutes on your own machine. Individual moves can and do change when they are searched further, which is why any single move in the report can be re-checked deeper before you act on it.
That the engine evaluated the position at that move number at worse than −0.60 from your side — roughly the point at which a position stops being a normal game to play and starts being one you have to defend. The move number is the checkpoint you picked when you started the check, and the report never calls it the end of your opening; it is the line the games are counted on either side of.
No, and the report will not say that. It can tell you that thirteen of fifty games reached move ten worse and that you scored 27% from those against 57% from the rest. It cannot tell you whether the opening choice, one tactic on move nine, the opponent or everything after move twenty produced that gap, and it does not pretend to. What it gives you instead is the list of specific moves behind those positions, each of which you can check on a board.
Ten, twenty-five, fifty or a hundred of your most recent matching games, at a checkpoint from move eight to move fifteen. The cost is a Stockfish search per distinct position, and games in one repertoire share their early moves — so a fifty-game check is a few hundred searches rather than a thousand. The dialog counts them exactly and estimates the time before you start, and the run then measures its own speed and tells you what is left. You can stop it at any point and keep every game it has finished.
No. The whole check runs in your browser on Stockfish 18 NNUE — nothing is sent to a server and nothing is charged. The two paid features on ChessLogix are the ones that call a language model on every use; this is not one of them.
Yes, because it is a report about your own games. Importing takes a public Chess.com or Lichess username and no password. Once games are in, the check reads whichever of them the filters select — one handle or several, one colour, one time control, or all of it.
That is what the filters are for, and it is worth doing. A line that holds at 15+10 can be unplayable at 3+0, and a serious account and a casual one produce different evidence about the same repertoire. Pick the handles and the time controls first; the report states which ones it was run over, and tells you when the filters have moved since.
Depth is yours to choose, from 10 to 20, and the default trades depth for covering more games. Treat the shape of the report — how many games, which openings, which move numbers — as the reliable part, and any individual move as provisional until you deep-check it, which searches that one position several plies further and updates the card with what it finds.
Pick the handle, the time controls and the checkpoint, and the check reports where those games stood and which of your moves cost the most. It runs on your own machine, it is free, and you can stop it at any point and keep what it has already found.
