There are automatically created compressed .jsonlz4 backups in the bookmarkbackups folder, only created when the calculated bookmark hash value has changed. You would have to decompress such a backup if you need direct access to bookmarks. *https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them The name of automatically created JSON bookmarks backups in the bookmarkbackups folder includes a total item count (folders and separators included) and an hash value to prevent saving the same backup more than once. You also see this count in the Library Restore menu drop-down list. *bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4. You can make Firefox create an automatic HTML backup (bookmarks.html) in the Firefox profile folder when Firefox is closed by setting browser.bookmarks.autoExportHTML to true on the about:config page. The HTML backup is created by default in the profile folder as bookmarks.html every time you close Firefox, but you can set the path and file name via a new String pref on the about:config page named browser.bookmarks.file and set its value to the full path of the backup bookmarks.html file including the file name. *https://support.mozilla.org/en-US/kb/about-config-editor-firefox