Most game analysis tools look at individual games. BlackboxChess runs Stockfish across your last 10 to 100 games and finds the mistake types that show up over and over. One bad game is noise. A pattern across 50 games is something worth fixing.
You connect your Lichess or Chess.com account, or upload a PGN file. Stockfish evaluates every position in every game and flags where you dropped significant material or missed a winning line. Those positions get classified into recurring mistake types.
The results are ranked by how much each pattern costs you on average per game, not just how often it occurred. A mistake that happens twice a game and costs 2 pawns matters more than one that happens once a month.
The system tracks dozens of mistake types across categories including material loss, king safety, piece activity, pawn structure, and endgame technique. Every flagged position maps to the specific type of error that caused it.
Most players have one category that's clearly worse than the others. That's the one worth working on first.
Lichess and Chess.com both have built-in analysis. They're good at showing you where you blundered in a specific game. What they don't do is tell you which of your mistakes is structural — the kind of thing that will show up again next game regardless of opening or opponent.
That's the gap here. The analysis looks across your entire recent game history to find what you actually keep doing wrong, not what went wrong on move 23 of Tuesday's game.
The free tier analyzes your last 10 games and shows your number-one mistake type. No account, no card required. The $10 full report covers 100 games, ranks all patterns by severity, includes three real game examples for each one with move-by-move context, and generates a short fix course built around your specific weakness. If the engine-verified analysis is factually wrong, you get a refund.
"I actually consciously took your analysis' advice today for a game and got my rooks in the game quicker than I would. Led to me having more attacking pieces to create threats with, which led to my opponent blundering under pressure and resigning."
BlackboxChess user
"Got my three weaknesses already — back rank blunders, unnecessary queen trades, losing my advantage."
Chess.com player, ~1200 Elo
"I can say that after trying, trusting and testing BlackboxChess, I am quite better for it and grateful. You've earned a serious fan of your work."
BlackboxChess user