Chesszest

What it is

Chesszest analyses your finished Chess.com games with the full Stockfish 19 engine running locally in your browser. It shows accuracy scores in your game history, grades every move on the board and turns your mistakes into personal exercises.

Why it exists

A complete game review is often limited or paid. Your computer is powerful enough to run Stockfish itself, so the extension does the work locally: no account, no server, and your games never leave your browser.

What you can do

• Ten built-in interface languages, selectable in settings and available offline
• Accuracy for both players directly in your Chess.com game history
• Every move graded on the board — best, excellent, good, inaccuracy, mistake, blunder — with the best-move arrow
• Grades for the alternative moves you try while reviewing a game
• Evaluation graph, key moments, annotated PGN and a shareable summary image
• Statistics over time by game mode: accuracy, rating, game phases, openings, opponents and recurring mistakes
• Exercises built from your own mistakes, with spaced repetition

How to install

Install this ZIP manually in a desktop Chromium browser. Your browser requires Developer mode and your confirmation to load the extension.

1. Download the zip file and extract it. Keep the extracted chess-precision folder somewhere permanent, for example in your Documents.
2. Open chrome://extensions in Chrome, edge://extensions in Edge, or brave://extensions in Brave.
3. Turn on Developer mode (top right in Chrome, left menu in Edge).
4. Click Load unpacked and select the chess-precision folder.
5. Pin the extension from the puzzle-piece menu, then open your Chess.com game history.

To update, download the new version, replace the folder’s content and click the reload arrow on the extension’s card.