Effective date: 2026-08-15

The short version: nothing ever leaves your browser. Stale Cookie makes no network requests of any kind — no telemetry, no analytics, no update checks, no crash reporting, no sync. There is no server. Everything described below happens locally, inside your browser profile.


Stale Cookie deletes browsing data (cookies, browsing history and, optionally, download history) belonging to sites you have not visited in a configurable number of days, and can clear the browser cache and saved form data globally on request. To decide what is stale, it reads data your browser already holds.

• Browsing history — the only source of "when did I last visit this site". Read during a scan, processed in memory, never stored by the extension.
• Cookies (all cookie stores, including Firefox containers) and, if you enable it, the download list — enumerated during a scan so you can preview and delete them.

All of this processing is local. None of it is transmitted, and the extension deliberately keeps no record of your visit times: staleness is recomputed from browser history on every scan, so deleting your history also deletes everything the extension could know about it.

• Settings, including your protected-sites list — in extension storage in your profile.
• Action log — a record of what the extension deleted (site names and item counts, never visit timestamps), in extension storage. Entries are deleted automatically after 30 days (with a 200-entry cap as a secondary bound), so the log cannot become a long-term record of the sites you once had data from.
• Error log — kept in memory only, capped at 50 entries; it disappears when the browser closes and is never written to disk.
• Undo snapshot — when cookies are deleted, a copy is kept in memory only so you can restore them; it disappears when the browser closes and expires 24 hours after the deletion, whichever comes first.
• Timers for the cleaning reminder and automatic cleaning.

None of this is shared with anyone, including the developer.


If you choose to export the logs (for example, to attach to a bug report), the export is created locally as a file you save yourself. The anonymize option is on by default: site names are replaced with consistent pseudonyms (site-1.example, …) and URL paths are dropped, so patterns stay diagnosable without exposing your browsing. Nothing is exported unless you do it, and nothing is sent anywhere by the extension.


Stale Cookie collects no personal data, no usage data, and no technical data. It shares nothing and sells nothing. There are no third-party services involved — the add-on listing platform (e.g. addons.mozilla.org) that distributes the extension is governed by its own privacy policy.


Uninstalling the extension removes its stored settings and action log along with it (extension storage is deleted by the browser on uninstall). The in-memory logs and undo snapshot vanish whenever the browser closes.


This policy lives in the extension's public repository; any change to it is visible in the repository history and will be noted in the release notes. The policy can only get stricter in spirit — "no network requests, ever" is a permanent commitment of the project.


Questions or concerns: open an issue at <https://github.com/SergioMartinezCid/stale-cookie/issues>.