I would quit surfing the Internet if this plugin would cease to exist Rated 5 out of 5 stars

Once upon a time there were browsers supporting vertical tabs. Every day this neat and useful function made life easier when surfing the Internet. One day some developers thought that no one would like to have life made easier and removed the feature. Because of that at least one person was getting more and more frustrated. Until finally it found THIS add-on giving back so much luxury and even more, no longer simple tabs but even tree style tabs. Tree style tabs the perfect tool for tabbed browsing!

This review is for a previous version of the add-on (0.17.2016061501). 

This is the only reason I'm using Firefox Rated 4 out of 5 stars

I love this plugin: this is the only reason I'm still using a Firefox.

There is a bug when tabs are hidden by user. Mouse is unable to do anything in area where tabs has been shown until resize of browser is performed.
Similar problem when you try restore tabs.

This review is for a previous version of the add-on (0.17.2016061501). 

this is way better than horizontal tabs Rated 5 out of 5 stars

this is the best way to organize lot of tabs

This review is for a previous version of the add-on (0.17.2016061501). 

Background open with Speed Dial Rated 3 out of 5 stars

Background open with Speed Dial add-on doesn't work.

This review is for a previous version of the add-on (0.17.2016061501).  This user has a previous review of this add-on.

Rated 5 out of 5 stars

Ditch Tab Group and Vertical Tabs Reloaded for Tree Style Tab.
Working nice too with Tab Wheel Scroll!

This review is for a previous version of the add-on (0.17.2016031101). 

Awesome addon Rated 5 out of 5 stars

Thank you for this awesome addon. I'm using it every single day for personal and professional reasons. I was wondering if there was plans to get it working with electrolysis (multi process firefox) Searched everywhere, no clues.
Once again, great work

This review is for a previous version of the add-on (0.17.2016031101). 

very fine Rated 5 out of 5 stars

we like tree style tabs ... please sak Mozilla to not deactive again tree style tabs

This review is for a previous version of the add-on (0.17.2016031101).  This user has a previous review of this add-on.

Great vertical tabbar, hides during fullscreen, & compatible with other tab extensions Rated 4 out of 5 stars

Great! This is one of the few vertical tabs add-ons that works flawlessly out of the box, including hiding during fullscreen videos, and fully compatible with all other extensions I'm using: Multiple Tab Handler, ColorfulTabs, Tab Mix Plus, Tab Kit Mouse Gestures, & Classic Theme Restorer (enable "squared tabs" option for compatibility with ColorfulTabs).

Unfortunately, it seems to be corrupting some of my tabs when restored with SessionSaver...

This review is for a previous version of the add-on (0.17.2016031101). 

brought the cruel title bar back Rated 4 out of 5 stars

Unfortunately this add on brought the useless, weird, shitty title bar solidly back and made it unavoidable.

This review is for a previous version of the add-on (0.17.2016031101). 

Less customization is not an upgrade Rated 2 out of 5 stars

Took away option to disable collapsible tree, which often happens when you don't want it to, particularly with a narrow tab bar

This review is for a previous version of the add-on (0.17.2016031101). 

Great Addon Rated 5 out of 5 stars

Very useful.

This review is for a previous version of the add-on (0.17.2016031101). 

Works in Ff v46.0.1 on Win7 home premium 64bit Rated 4 out of 5 stars

Works in Ff v46.0.1. Supports theme-translucency/dev-colors. Allows tab-bar placement top, bottom, left or right=my preferrence. Other(s) I've used and preferred are not compatible with this Ff version, however I may come to like/keep Tree Style Tab. When tried in the past it always broke something or conflicted with another add-on, didn't play well with themes etc. Admittedly it has been some time since I last tried this add-on, so to be fair I decided to try it again. Seems to be much improved and worthy of continued use at this time. [comment regarding close button edited/updated below] Further experimentation with other add-ons to come. Setting up a fresh new Ff install as of this writing. If I can update this review later I will. Otherwise, give Tree Style Tab another try if like me you had problems with previous versions. It's outlasted most of the other vertical tab add-ons with exception of few and seems fairly popular, so give it a whirl. Seems to do what it says on the box!

Update 5/18/16:
Regarding my comment; "I do agree with other posters who complain about the close button on every tab. It looks hideous and should have an option to only show on current highlighted tab IMO."

That said, I still think an option for the users choice (single tab or all tabs) should be included, however, I'm using a dark theme for Ff and interestingly enough tabs are not outlined/defined visually with exception of the active/highlighted tab in use. Only the site icon, tab title, and close button-(X) are seen on each tab including child tabs. The close button is the only indication that there are child tabs as they are progressively shorter and therefore the close button-(X) on the right end of each tab forms an outline to indicate child tabs. SO, in conclusion, it appears the close button on all tabs is a plus in this instance. Without it on each tab I wouldn't know which are parent and which are child tabs unless I were to run the mouse cursor over each tab for a suttle highlight to clue me in. As it is, I can instantly see which are which at a glance. Interesting!

This review is for a previous version of the add-on (0.17.2016031101). 

Tree Style Tabs Rated 4 out of 5 stars

This is a very useful add-on, but I've got some minor problems with it. First, the close buttons are a bit annoying. They should only show if you hover over the sidebar. And while it does adapt well to my theme, the new tab button remains white. Finally, the overall scale of the buttons is too small, especially on my QHD monitor. I hope you can do something about this. I am torn between the Test Pilot add-on Tab Center and this, I wish someone would combine them :)

This review is for a previous version of the add-on (0.17.2016031101). 

Tabbar position on bottom not working Rated 3 out of 5 stars

Tabbar position on bottom not working

This review is for a previous version of the add-on (0.17.2016031101). 

天才 Rated 5 out of 5 stars

すごい便利。ブラウザのデフォルト機能にした方が良いと思う。ぜひChrome版も作って欲しい。

This review is for a previous version of the add-on (0.17.2016031101). 

Almost works with Firefox 46 64 bits in Win7 Rated 4 out of 5 stars

Almost: new created tabs don't show nor one of the pinned, so almost but really good already :)

This review is for a previous version of the add-on (0.17.2016031101).  This user has 2 previous reviews of this add-on.

Awesome add-on Rated 5 out of 5 stars

I'm using this addon for years now and it is for me the best I ever found. Easy to use, intuitive, and without bugs. A great tool to structure tabs.
thank you Piro for your great work !!

This review is for a previous version of the add-on (0.17.2016031101). 

The best, but with bugs Rated 4 out of 5 stars

Every so often the pinned tabs get all messed up, with pinned tabs partially showing. Even restarting does not fix it. Would be great to see this issue fixed. Possibly a conflict with Tile Tabs?

This review is for a previous version of the add-on (0.17.2016031101). 

Tree Style Tab - The Best Rated 5 out of 5 stars

This is the best vertical tab menu system, I've used. I've been using it for a long time and it really makes Firefox usable. Please keep up the good work, keeping it simple, clean, and functional. Thank you!

This review is for a previous version of the add-on (0.17.2016031101). 

tree style tab & session manager are best addone Rated 5 out of 5 stars

tree style tab & session manager are best addone

This review is for a previous version of the add-on (0.17.2016031101).