Your games stay on your device.

Data processed and stored on your device

You can import a PGN game or enter a chess position to analyze or explore it. Stockfish runs locally in the extension using bundled WebAssembly and JavaScript worker files. PGNs, game details, positions, and analysis are processed in your browser; no account or login is required.

Browser storage

• If you save a game in the extension’s PGN library, its PGN text, the name you choose, and the save time are stored in IndexedDB.
• Position-analysis cache entries—including position FENs, engine evaluations, and lines—are stored in IndexedDB. If you install it, the optional precomputed-position database and its metadata are stored there too.
• Extension preferences such as language, theme, sound, engine depth and MultiPV, cache and database options, board orientation, and board theme are stored in chrome.storage.local. This is local extension storage, not Chrome Sync.
• The extension estimates local browser storage usage for display in its settings.

Clipboard and exports

Position/FEN paste and PGN copy use browser clipboard APIs only in response to your action. Annotated PGN and analysis JSON exports are generated locally and downloaded by the browser. The extension’s chess sounds and Stockfish files are bundled; they are not fetched from a sound or engine service at runtime.

Extension permissions

• Storage: used to save extension preferences and precomputed-database status in local extension storage.
• Downloads: the extension does not request this permission. Exports use a browser-created download link, not the chrome.downloads API.
• The current manifest declares no host permissions or content scripts, and no tabs, activeTab, history, or browsing-data permissions.
• The background service worker opens the extension’s analyzer page when you click its toolbar icon and opens the setup page after installation.
• Web-accessible resources make named bundled files, such as Stockfish and other assets, available to matching pages. This does not give the extension access to the contents of the websites you visit.

Optional network request

If you choose to install the optional precomputed-position database, the extension makes a GET request to download it from site-blocker.info. The request omits credentials and does not include your PGN, FEN, settings, or analysis in its URL or request body.

As with a normal web request, the server may receive connection information such as your IP address and standard browser or network headers. The extension’s source code does not establish who operates that host, what its server logs contain, or how long those logs are retained.

The current manifest declares no host_permissions, even though the source attempts this optional request. Whether the download works in a published build should be verified; if Chrome requires host access, only the necessary permission should be requested.

Sharing and third parties

The current extension source has no analytics, advertising, account, or user-data upload integration. The optional database download described above does contact an external host. This description covers requests made by the extension itself; normal Chrome Web Store and browser traffic is outside the extension’s code.

Your choices and data controls

• The precomputed database is optional. You can install or remove it in the extension settings.
• You can delete saved games from the PGN library and clear cached analysis in settings.
• Uninstalling the extension or clearing its site or extension data through Chrome may remove locally stored extension data, subject to Chrome’s behavior.
• Deleting local extension data does not delete any server logs that may have been created when the optional database was downloaded.