What is ChessBlunders.org?

Updated

ChessBlunders.org is a chess training site that analyzes your games with Stockfish 16 to identify your blunders, then turns those specific mistakes into puzzles you can practice. It is aimed at players who want to improve by fixing the exact errors they make in their own games, rather than drilling generic tactics. The site describes its purpose as turning your mistakes into improvement.

How it works

The workflow follows a simple loop: analyze, identify, practice.

  1. Analyze your games — You submit your games, and the site runs them through Stockfish 16 to evaluate the positions.
  2. Find the blunders — The engine flags the moves where your evaluation dropped significantly, isolating the moments you went wrong.
  3. Practice them as puzzles — Those blunder positions become puzzles. You replay the critical moment and try to find the correct move, so the lesson is tied to a position you actually created.

The expected result is that you repeatedly face your own recurring mistakes until the correct response becomes familiar.

What problem it solves

Most improvement tools fall into two categories, and ChessBlunders.org sits between them:

Approach What it does Limitation it addresses
Plain game review Shows you where you went wrong You see the error once and may forget it
Generic puzzle sets Trains tactics from other people's games The positions may never occur in your play
ChessBlunders.org Extracts your own blunders and makes them puzzles Combines personal relevance with repeatable practice

The core idea is that a blunder you actually committed is more memorable and more useful to drill than an abstract puzzle, because it reflects a pattern in your own thinking.

Who it is for

It fits players who:

  • Already play games (online or over the board) and want a structured way to review them.
  • Notice they keep making similar mistakes but struggle to stop.
  • Want puzzle practice that is personalized rather than random.

It is less useful if you are looking for opening theory, a playing platform, or human coaching. The site's focus is narrow: engine analysis of your games plus puzzle practice built from your blunders.

What to keep in mind

  • The analysis depends on Stockfish 16, so the quality of the blunder detection is tied to that engine's evaluation.
  • The value comes from the loop, not a single session — you need to feed it your games and return to the puzzles to see benefit.
  • The site's public description does not state pricing or account requirements, so check the site directly before assuming how access works.