Absolutely necessary. Adds functionality that FF should have out of the box. And does it quite well. Also the only tab manager across multiple browsers I've had no issues with. Can't recommend this enough. Though it doesn't always save correctly on closing. Just manually save before closing. Shame, but at this point I'm not even knocking off half a star for it.

Saved me today, fuck

Sehr nützliche Erweiterung! Hat bei mir die Lücke zwischen Tabs und Lesezeichen gefüllt. Gerade für Forschungsarbeit ist es sehr praktisch, da ich so immer weiss, dass ich nach einem Absturz (oder auch sonst) meine Sitzungen wieder habe. Plus, ich kann ganz einfach eine Sitzung zwischen Geräten verschieben xD

yes, at last firefox doesn't randomly delete all pinned tabs. thanks

I forgot I had this installed and it just saved my butt. For whatever reason, a Firefox window would not open after closing and restarting my PC. Tried a lot of things to get them back but then remembered this add on. Needless to say, I got my lost window back.