I've used Tree hierarchy add-ons since forever. Came from Tree Tabs most recently, but the sessions didn't work correctly, decided to look for alternatives. This add-on is amazing. The holy grail of Tree Tabs add-ons.

Top 3 stuff I enjoy:
- Groups and containers.
- Working snapshots (e.g. sessions loading)
- Highly customizable

The most features-full, esthetic, and practical sidebar.
Only downside is sometime minor bugs with tabs (disappears or wrong container), but reloading the add-on fixes it. Also the add-on is maintained and updates are frequents.

I can't switch to Chrome if I wanted: there is no Sidebery!! This works amazing. Firefox Containers gets you ready and Sidebery finishes it of. I used to have over 40 tabs. Now I still have over 40 tabs, but I grouped them into Work, Personal and Learning. Each showing only a dozen or so, bringing back my sanity :-)

Its beautiful. It works really really well.
The most underrated extension in the category of sidebars.The possibilities are endless. I keep discovering new features everyday.

Tabs on the side; Containers; Bookmarks; So feature rich! I've removed the default tab bar and used this add-on to replace it completely.

The BEST tab manager, I always loved TST but it was lacking some features which I needed like tab grouping. I discovered this recently and it is extremely customizable even suspends tabs automatically. The perfect tab manager I've been looking for. Thanks for the developer for creating this extension. Will never leave Firefox because of extensions like TST and Sideberry alone.

I came back to firefox because of TST and Sidebery made sure I'll stick with firefox. It does everything I missed in TST and looks beautiful. Animations where kind of laggy for me but you can turn them off in settings, so problem solved. Awesome extension, love it <3

Absolutely amazing extension. So many options for customization..

I have been using vertical tabs extensions since they started making them. I think this is the best looking one and really customizable. Thank you.

The Perfect plugin!!! thank you

does everything piroor's tree style tab does (the core functions I used anyway) + it works with tab saver extensions without losing the tree hierarchy.

This should be a recommendation from Firefox