The best currently for Quantum.

Thank You So Much Dear "Sienori" , For This Brilliant addon , Excellent addon

excellent, the best session manager at the moment. if i may, i'd like to point out a little problem regarding favicons and (i think) "auto tab discard" extension: when TSM saves a session with some "discarded tabs" by that extension, the modified favicon disappear when reopening the session.

Works great but the only issue I have is when i restore a session sometimes it will also restore my bookmarks and open them up in tabs so a session that was like 5 tabs when I restored it suddenly has over 100 tabs.

This is a must-have, life-saving add-on! Ever since TabMix Plus stopped working, I was looking for an add-on that would ensure that my tabs are restored when Firefox has a bad crash and can't restore itself.
But this add-on does so much more. It allows you to store your session manually or automatically. So whenever you notice that you are missing a tab (web page) from a few weeks ago, chances are good that you can find a backup.

Phenomenal!! Essential for my productivity. Cannot recommend highly enough

Does Tab Session Manager supports Simple Tab Groups? What should I do if FF suddenly crashes? Will Tab Session Manager restore all my tabs AND GROUPS?

>>>PLEASE ADD ABILITY TO "LOCK" SAVED SESSIONS! The delete button is not forgiving, (no undo/undelete...and the "restore" option only lasts a few seconds!)....so please add option to LOCK, located next to the OPEN and DELETE options. thanks...great app. *********please update as soon as you can! THANKS AGAIN! :)

OPEN - DELETE - LOCK!

this is a great little add-on. so many times, while drunk i have closed windows to come in the next morning to wonder where they went. Thanks

Tab Mix Plusのセッションファイルをインポートするのは可能でしょうか？前からはそっちを使っていましたがつい最近動作がおかしくなりこちらに移行するのを決めましたけど、今Tab Mix Plusではなぜか保存してるタブの1割程度しか復元できない状態ですから、もし変換が可能ならぜひ試してみたいです。
ちなみにブラウザはWaterfox使っています。
不慣れな日本語ですみません。

It saved my life a few times already. A few months ago firefox started crashing and losing all tabs on linux, and after I installed this addon I had a few crashes that I survived and had a way to restore all my tabs. A real life saver.

Frequently looses tabs in the middle (not the oldest nor the recent one) of list. So it`s not noticeable at firefox startup that tabs are lost if 150+ tabs are opened. What`s even worse is that tabs disappear not in a whole chunk but in few chunks in the middle. Lets say we have 150 tabs. So it`s not tabs 35-75, for example that are lost, but rather tabs 35-40, 60-70 and 90-100 will be gone. So this is not noticeable at first glance. Review is from 1 september 2019 version, as i have changed my previous review as i wanted to support the author and expected better resiliency.

I've only used this for a few weeks but I feel like this add-on has changed the way I browse already. It's wonderful to save sessions for different purposes, like one session of looking at Emulation websites, one session for seeing sites about a certain game/show or another session for my work/email. No longer do I have to keep one of each around to switch to a different kind of browsing and have the associated memory usage. I can open my browser to a single new tab and use session manager to find the session I want to use. I give it 4 instead of 5 due to a IndexDB issue which thankfully solved itself upon browser reboot, it hasn't popped up again but it does pose a reliability issue for the add-on.

Highly recommended, should be a feature for stock browsers in the future IMO.