Unlike Firefox for desktop, the native Firefox Mobile for Android devices do not have any advanced cookie management options, including a setting to delete all cookies when the browser is closed (ie, turn all cookies in session cookies), which improves user privacy by preventing sites and web trackers from persisting data across browsing sessions. This problem is exacerbated by the lack of a setting to reject third-party cookies — there is an option to disable all cookies, but using it also prevents any benign cookie usage (eg. login to sites). There is a feature request open to add these options. This extension solves this problem for now.
New features and development
This add-on was born to solve a very specific problem and no new features are planned for the short term. A possible enhancement is to allow white-listing of cookie that may persist across sessions but, since I do not use Firefox Mobile for extended website logins, I am not sure if it is worth the development effort, but any developer interested in such feature is welcome to write it.
All development is done in GitHub and comments and feedback are welcome. The
repository is available in https://github.com/ittner/delete-cookies-on-exit