From MozillaZine Knowledge Base

The bookmarkbackups folder contains bookmarks-(date).html files (daily rotating backups of bookmarks.html) or, starting in Firefox 3, bookmarks-(date).json files (daily rotating backups of bookmarks stored in places.sqlite).

Moving

This folder can be moved to a different profile without any extra effort.

Deleting

Deleting this folder will cause the loss of all bookmarks backups. It will be regenerated when it is needed.

Related files and folders

• bookmarks.bak
• bookmarks.html
• bookmarks.html.moztmp
• bookmarks-(date).html
• bookmarks-(date).json

Related bug reports

• Bug 305004 - Create a dated bookmark backup file periodically
• Bug 384370 – use JSON as the on disk, lossless format for our bookmark backup

See also

• Lost bookmarks
• Browser.bookmarks.max backups