Not possible to store to do's and other information in bookmarks, but rather on file Rated 2 out of 5 stars

It would be reliable if it was possible to store data (to do's...) in bookmarks and synchronize it with X-marks.
Automatically without need to import or export to backup.

But instead all data must be manually exported and imported. In the event failure or other things, living the last backup/export which might be three months old to be what you might be left with in case a crash.

So not too reliable to store data or rely on, but good design.

This review is for a previous version of the add-on ( 

Synchronizing reminders

Ensuring that there is no data loss is an important part of any reminder or ToDo system. While ReminderFox currently has no server-side storage of its own, it offers full synchronization support so that you can synchronize reminders with other computers, or just use it to keep a remote backup. See the details here:
Alternatively, many users have used Dropbox to get automatic backup by simply storing their reminderfox.ics calendar file in the Dropbox folder.
Thanks, Tom.