Best of the best. I was looking for something similar, very pleased with the result. We just have to wait to hide the tabs at the top ((
upd'2024: ... and search in opened tabs by caption please ))

tes

My favorite and most used Firefox plugin. Increases my daily productivity and ease of mind significantly. Also the main reason why I stayed with Firefox for years (even though Chrome was and is very tempting). The overhaul update of this plugin which now supports Firefox full screen mode on Mac OS and got rid of all other bugs I noticed before is stunning! Love it!

很喜欢这个扩展。

It's come to be an essential extension for me. With the death of tab groups it's the next-best-thing. I only wish that there was a better way of creating group folders (dummy tabs).

Edit 2020-04-30: Still loving it

方便整理各式各樣的網頁，可以一目了然網頁之間的關係

Must install add-on

This extension is super easy to use. I love it!!!

Dhvhggjj

Tree Style Tabs is indispensable, and I'm so happy you got a WebExtensions version in time for Firefox 57+.

The latest version seems to have a bug where the tabs don't always update (eg. new tabs aren't shown in the sidebar) but it was working great before this version. Been testing this since the first WE compatible version was released.

great way to create semantic relationships between tab groups

Problem with FireFox Quantum.
It is not possible to display two panels, left and right at the same time.
In the previous version firefox (56.*) it was possible to display bookmarks in the left panel and on the right opened tabs at the same time.
Now, in FireFox Quantum, only one panel is available, left or right at one time. Open tabs are displayed at the top and do not depend on whether the Tree tab is enabled or not.

exactly what I need!! since years indispensable for any desktop web junkie who wants to use more than 10 tabs...

It's awesome. My wide-screen monitor is finally useful.

Very customiziable and does exactly what I been looking for.