Even when the firefox history allows to open closed windows and tabs, there are occasions that can brick this feature.
This addon saved my life already once - and its a good reminder to clear my tabs everytime save enother session with 900 tabs :O

does not work with Firefox 'tab groups'

by using this add-on, I could safely close lots of tabs after working, and restore those tabs in next day. Love it!

Very good tool to save, manage and edit sessions for later use, much more clear oversight than all those tab grouping functions or add ons!
Pay attention: I recommend disabling the "auto save" feature in the settings, because otherwise your library will overflow and be incredibly difficult to manage. Save sessions manually, or when you close your browser!

It has many features... but lacks the most important one: it saves open sessions as new ones, not updates them!!
Still cannot find a replacement for the old good Sync Tab Groups........ :'( This one is NOT.

Works well generally. I'm waiting for it to support tab groups!

Does an excellent job saving tabs. I wish it would include saving tab-groups in Firefox as well.

Вспомни моменты, когда браузер закрылся и после запуска нет 100 любимых вкладок и ты проспал запрос о восстановлении... Теперь такого не будет! Настрой сохранение при закрытии, 10 копий (или больше) и работай без страха.

perfect for me

Worked well for years. Sometime last year it broke, all my sessions disappeared from the list and it will only save the last session. I think I did something that fixed it, or it fixed itself and I was able to get all my stuff back (thought I am unable to recreate what I did).

But now it has happened again and this time it does not seem recoverable. The export option in the extension settings does not even work.

Not reliable, wish I could rate it higher but I am now screwed because of this. So much time will need to be wasted to get all my research and prep work back.

Find an alternative that doesn't break/wipe itself as much and has more reliable backup methods.

Absolutely love this add-on! But the default settings are pretty frustrating, only saving the last 10 sessions and auto-saving every 15 minutes...

For some reason, my custom settings reset to default once or twice a year. It could be my mistake, but just two hours of not noticing can wipe out all previous saves.

It’d be much less of a headache if the default values were a bit higher, like saving at least 50 sessions and auto-saving every 30 minutes. That way, we’d have a little buffer.

Great extension, after last update, I had to remove extension and related files, and install again, after that all sessions became to auto save again normally! Thank you

I loved this extension, it did exactly what I needed it to, but the "open" button has suddenly stopped working. I tried removing and reinstalling the extension but I have no way of opening sessions anymore. I can only click on each link one by one. If this is fixed, I'll revise my review.

Documentation / Readme is insufficient. Cannot see what the Tab Session Manager is actually supposed to do and how to use it. What makes it worse, is the author's poor command of the English language. In Settings, file paths are not shown, and apparently cannot be set. All in all the whole thing seems too complicated to me. On top, when experimenting to make sense of the extension, it repeatedly crashes and takes the browser with it. A waste of time.

Does not even appear on the toolbar or anywhere else - so no idea if it actually works or not. About to uninstall and find something else.

I had been using it for a long time without issues, it saved me 2-3 times; but yesterday my computer crashed. My waterfox session file must have been corrupted and it restored it from the recovery one (previous.json) that is somehow 2 months old (thank you mozilla for not updating it more frequently). I immediately went to tab session manager to restore; but surprise surprise, all the backups are gone. At some point it seems the automatic backup feature stopped working and somehow even the older sessions disappeared. Idk if it was a browser update, error or that they were older than X and automatically deleted.
TLDR, even having this extension enabled to prevent the loss of my session, I still lost my session. I will either look for an alternative extension and/or start backuping the session file manually.

Would be nice to be able to save Tab Groups also.

all tabs re-opened, but tab groups are destroyed

Did not save my fucking tabs.