How do I merge a backup of my bookmarks with my current version?

In Firefox the bookmark backup files are in JSON format, which doesn't allow that backup file to be merged with existing bookmarks. Restoring a backup would overwrite your existing bookmarks. But if you would '''export''' your existing bookmarks in HTML format, you could '''import''' that HTML file to append / merge after restoring the backup. https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them#w_restoring-from-backups