They charge your account without notice. They do not respond to requests for help/refund. There in not a place for a user to view, edit, or remove the personal information that they have on file for you (just try and find SOMETHING). I can't speak to the app, as I never used it; but your personal information is blowing in the wind if you give it to them. As Mozilla says above: "This is not monitored for security through Mozilla's Recommended Extensions program. Make sure you trust it before installing." Trust: NO

doesn't work for mobile browser, which is the platform where private bookmarks are most needed..