Offline Chess Analyzer by NoobieDoobie
A Firefox extension that reviews your chess games on your own machine — Stockfish in a WASM worker, an offline opening book, and not a single position leaving the browser.
Available on Firefox for Android™Available on Firefox for Android™
Scan the QR code to open this extension in Firefox for Android
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About this extension
The extension opens its own analysis page — it does not overlay chess.com or any other site — and runs the
engine inside that page. Load a game and every move is graded; step through it, or stop anywhere and play your
own line to see where the alternative would have gone.
engine inside that page. Load a game and every move is graded; step through it, or stop anywhere and play your
own line to see where the alternative would have gone.
- Whole-game review that classifies every move with an Expected Points model, running across a pool of engines.
- Real opening-book classification (
Book) from an offline ECO database, not a guess from move numbers. - Terminal positions decided by the rules — checkmate, stalemate and draws are scored directly instead of
being handed to the engine. - Evaluation bar and timeline scrubber, in pawns or expected points.
- Interactive what-if play from any position in the game, including underpromotion.
- An unbounded move tree — every alternative you play becomes a variation under the move it branched from.
- Live MultiPV analysis of the position on the board, with a best-move arrow.
- Board and piece themes, board flip, and a reset that drops back to the reference line.
- Trap finder — moves that are sound for you and that opponents at your rating tend to
answer badly, found by crossing the Lichess opening explorer with the local engine.
- PGN paste, or a custom start FEN.
- Player Elo picked up from the PGN tags (
WhiteElo/BlackElo) when they are there. - One-click import from a chess.com archive.
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Permissions and data
Required permissions:
- Access browser tabs
- Access your data for www.chess.com
Optional permissions:
- Access your data for www.chess.com
- Access your data for api.chess.com
- Access your data for explorer.lichess.org
Data collection:
- The developer says this extension doesn't require data collection.
More information
- Add-on Links
- Version
- 0.1.0
- Size
- 12.23 MB
- Last updated
- 11 days ago (Aug 13, 2026)
- Related Categories
- License
- ISC License
- Version History
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