Sadly, currently broken.
It guzzles memory and CPU time like nothing else I've ever used and really slows down the browsing experience. This addon should *not* be going to 80% CPU usage and adding 2-4GB of RAM usage just because I opened a single tab.

I hope it gets fixed soon.

edit: My mistake. The real cause of the problem was one of the settings in the Tab Session Manager.
5/5 for Tree Style Tab itself.

A must-have add-on.

So glad to see this back in Firefox Quantum

It totally changed my internet browsing experience! I don't need to search where was that tab. I know where I got there from (on which page I clicked a link when new tab was opened). I know which crappy site opened a new tab without my permission. I can close whole "topic" of tabs. It is like the already existing tab-groups but evolved onto a higher level and on steroids. Problems? There are some: firefox memory limits and the fact that my browser often has 1k+ tabs opened at a time. Over a thousand - and it still works :D Don't try this on chrome or safari. Not even mentioning IE. TreeStyleTab is just great. And user experience is nice as well (Piro provided links on how to deal with UI restrictions - could be more permanent/readable but it is there.... to solve issues that he couldn't do on his own).

A great add-on. May I propose an idea? ) It would be great to have, as an option, side-tabs colored depending on tab domain.

My favorite addon! Though currently when I reopen my second window, it usually forgets the tab tree structure (un-indents all tabs). Otherwise it's perfect.

Vastly improved my tabbing experience. A must for everybody!

Vraiment pratique et complet avec les addons TST. bravo

This is an awesome add-on.
Especially if you keep like 200 tabs open. It allows to organize them in a simple way.

Dear Piro, I really need your help. Last version of Firefox seems to lose internet connection when TST bar is open. I know how strange it sounds, but I confirmed that on two computers already. Having TST installed does not break anything, but if you open the sidebar, connection disappears in the next minute. But the second I close the sidebar connection restores. I will check if the issue persists if I disable other add-ons.
Please get in touch at vwa8ypaq65ts@mail.ru. I would really hate to uninstall TST.
Thanks,
Alex.

This is the best add-on on firefox. Everyone's lives would be better if they used tree-style tabs. I am a tree-style tab evangelist and the add-on is the primary reason that I use firefox.

Tab power at your finger-tips

Tree Style Tab is the main reason Firefox has been my default browser for the last several years. It is hard to believe that Firefox--nor any other browser from Chrome to Edge to Opera contains native support for these style of tabs. For any user that like to have more than 20 tabs open at a time, I find this to be essential. Absolutely the best browser feature, I just wish I could figure out a way to make a monetary donation to the developer!

Great addon! Without Tab Groups it is a lifesaver when working with lots of tabs.

All the issues have been fixed! Flat out, this extension is the main reason why I use Firefox, I can't stand Tabs on top; they are a mess when there are more then 3 open tabs! No other browser handles tabs on the side well. Chrome's similar extensions are all horrible. Edge and Vivaldi don't handle "tab children" the same way and you can't tell what tab a new tab is from if you do "Open in new Tab".

And then add in all the other addon Extensions that Piro has made for TST, it can't be beat.

I utterly fail to see why this sort of thing isn't just an option for ALL browsers. I guess it just shows how technical of user I and others that need something like TST are.

ko

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 ))