EDITED: All my tabs are still there, the addon is perfectly working for me. But it seems it's not the case for most of the users here. I don't know why it's working for me, and not for other users. I suggest you to use another addon, that seems better now: better-onetab instead. Because Onetabe hasn't been updated since 2017, it really seems it's not maintained anymore!

My previous review: It doesn't lose your tab, and if you want to be sure it'll never lose any tabs, the extension lets you save them to the disk in a html format, very handy.
This is the extension I use to keep my sessions, close in one click the tabs when I have many many, and save them. One of the best memory saver.

I lost all my tabs when restoring them from the page.

Only after a while I realized how helpful this add-on is! I am using it now all the time.

OneTab lost all my tab data many times. I thought that maybe automatic upgrades/updates on Firefox may have been the culprit, but having just reinstalled it for the first time in a while, it immediate lost many windows of data for me, IMMEDIATELY after clicking on bring all windows into One Tab. Thanks, One Tab.

Дополнение рухнуло. Все сохранённые вкладки пропали.

WOW

The functionality is good; however, the irritation factor is over-the-top. When I start my browser, OneTab presents itself every time regardless of what I choose as my home tab. Yes I know OneTab is there; I don't want it in my face when I don't need it. The functionality is not worth the aggravation.

OneTab lost a whole group of tabs, not for the first time. This extension is no longer maintained - use at your own risk.

Excellent add-on that does exactly as it claims. Secure way to 'park' your browsing session before restarting your computer or making a collection of frequently accessed sites for easy browsing. Nice work guys, thanks for your efforts!

Es muy útil y todo, pero deberían cambiar la interfaz y más que nada hacer los enlaces al compartir duren más, por lo menos 1 semana.

Works great, I love this add-on.
My only suggestion would be to add a right click context menu option for OneTab once a specific tab is clicked, so that I don't need to have the icon constantly in my toolbar.
I feel like this used to be an option, but I don't see it anymore so maybe I was mistaken.