by Daniel Dawson (Developer) on Noie. 14, 2014 · link permanent

The data is and always has been stored in your Firefox profile (assuming you're using this with Firefox). I suggest you read this article: https://support.mozilla.org/kb/profiles-where-firefox-stores-user-data . It tells you everything you need to know, namely how to find your profile and which files correspond to your saved passwords. All you need to do is make copies of those latter files, and to restore such a backup, copy them back while Firefox is not running.

There's also this add-on: https://addons.mozilla.org/addon/password-exporter/ , although it may no longer work, if recent reviews are anything to go by. It's worth testing, though.