Had 64 open tabs and it only converted 4 of them :(

Absolutely useless. After restoring tabs Firefox tried to load content of all tabs at once which resulted in an infinite loop of loading without any result. Had to kill FF with the Task Manager. Lost all tabs. Avoid.

Je ne trouve pas comment régler l'extension sur firefox (en cliquant droit sur le logo de l'extension) alors que c'est possible sur chrome. Arrangez ça svp.
Sinon pour régler les options il suffit de cliquer sur le bouton de l'extension et une page s'ouvrira...

I tried this add-on today, having so far been fairly pleased with it on FF for Windows. I had 30 tabs open on FF for Android. OneTab saved the most recent three and deleted the other 27 from existence. The fail is impossible to exaggerate. I will probably remove this and hunt for alternatives on FF for Windows too.

Used to have this on Chrome in 2018, worked. That's why I trusted it and didn't export.
Now, in 2020 on Firefox/MacOS, didn't restore 48 tabs, but removed them from the list. Hours of work destroyed, no chance to know which 48 of ~ 1000 tabs were relevant to me.

I never write a review for an extension but this one deserves more than this few words.
I've started using this ext since my 2010 notebook started lagging so hard and I've allways been a multi-tab-user, the "share as web page" helps me to change my tabs into devices and to share colleague my current work focus. The right click OneTab in any website is really helpful as well, because you cand send a website into any different tab group and send tabs in any direction to a new group.
These guys/girls did an amazing job with OneTab, it's a simple extension that does a lot of dirty work.
What I would add to OneTab ? Maybe some kind of box to select tabs so you can select some tabs from different groups and you can share them or remove or whatever. And a search box to search from tabs when you have a lot tabs and want to find one quickly.
Excelent job, got my five stars and my first review. Keep on it !