In both desktop and mobile versions of Firefox you can enable "Delete cookies and site data when Firefox is closed". On Desktop you can click "Manage Exceptions..." to whitelist specific sites. https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox https://support.mozilla.org/en-US/kb/clear-your-browsing-history-firefox-android This feature appears to be missing on Android. Is this planned? Is there an about:config method to manage these exclusions? I am using the Nightly version on Android.