It saves all opened tabs in .html file. It imports all href from selected file. (It can be html or any other text based file).
I did it as a gift for my wife - she has hundreds of opened tabs and we weren't satisfied with the available solutions of tabs backup.
If you have a wife with similar needs, try these add-on and make her happy. ;-)

Install

• License: Mozilla Public License 2.0
• Weekly downloads: 0
• Average daily users: 11
• Rating: 0/5 of 0 ratings
• Created: 2021-02-20 19:01:29
• Last updated: 2021-02-21 19:05:15
• Homepage: https://github.com/BeroNizic/backup-tabs
• Support site and email
• Orig: https://addons.mozilla.org/en-US/firefox/addon/backup-tabs/
• API: {301ec43b-6cd0-46c4-9f78-aef1555b0dc5}