Brilliant! One of the best extensions I've ever used, honestly!
Funny that I had it installed for a year now, along with all the other vertical-tab extensions that I could find, and I didn't really saw what it can do until recently..
It has so many essential features for my productivity, workflow and tab/bookmark management.
Congrats and thank you!!

Really excited to find this extension! Was long term user on Tree Tabs and TST, but this one looks much cooler. And good looking without additional css rules. One flaw, I think white theme should be used by default, it is cool that dark theme also exists.

I'm using it for couple days only, but I like it much more than Tree Style Tab. Love the "Panels".
Finally tab-organizing addon I might be happy with.

The best tab management extension for Firefox among all I've tried thus far (and I've tried a lot of them)! Very flexible, highly customizable and good looking. Very well designed!

The best side tabs ever. It has also container URL rules and User Agent URL rules for containers. Works much faster than any other side tab extension I have ever tried.

The best vertical-tree-style-tab extension (and I have tried a few before). A lot of great options and features, e.g. automatically moving a new tab to a defined panel based on the url pattern. It sometimes crashes after Firefox restarts, but the feature of periodic auto-saving snapshots provides a rescue. Thanks!

This is the best addon I've ever experienced on Firefox. Way superior to Treestyle tabs or OneTab for organizing my tabs. This addon is loaded with excellent features like proxy, useragent and container support.
Thanks to panels and tab saving you can organize and backup your sessions with snapshots without any hassle.

This addon is the only reason why I didn't ditch Firefox for Brave yet.

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.