User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.0 Build ID: 20150826023504 Steps to reproduce: I downloaded Ubuntu under the following URL and installed it in Virtualbox: ftp://ftp.rrzn.uni-hannover.de/pub/mirror/linux/ubuntu-releases/14.04.3/ubuntu-14.04.3-desktop-amd64.iso The sha1sum of the ISO is: a3de42e9b563f3ccf100fa84f4f7c831e659320f I updated the installed system after that and began my tests. The tests can be found in the screencast file included with this report. Actual results: The results of the tests can be found in the screencast file included with this report. Expected results: After a user deletes all cookies and the history through the Firefox settings and also deletes the cache and any offline-data in the settings PouchDB should forget about any data that was saved within it. I'm not sure about the potential impact of this issue or whether it is a bug or a feature. But I believe that a malicious website could continue to track a user's behaviour if the user returns to that website even after the user used the browser's standard settings to clear cache, cookies, history and offline-browsing data/cache. The only way I found to get rid of the PouchDB data is to delete the Firefox profile. I was also able to reproduce this error/"Firefox feature" (?) in Windows 7.