Tree Style Tab is a WebExtension now

Martin Brinkmann
Sep 27, 2017
Firefox, Firefox add-ons

The developer of the popular Tree Style Tab add-on for Firefox has published a new version of the add-on to Mozilla AMO that is a WebExtension.

Tree Style Tab is a long standing add-on for the Firefox web browser that moves tabs to a sidebar to display them there.

The sidebar holds more tabs in the visual area of the browser window than the Firefox tab bar, and it frees up vertical space as well by hiding the tab bar automatically. Also, it makes it a lot easier to reorder tabs using drag and drop thanks to more tabs being displayed at the same time.

The WebExtension version of Tree Style Tab is somewhat limited right now, but it ensures that compatibility with Firefox 57 is there and that development will continue.

Side note: The extension made a jump to version 2.0 from the previous 0.19 to indicate the major change. It is compatible with Firefox 57 and newer only. Users who run Firefox 56 or older need to keep on using the legacy add-on version of Tree Style Tab for now.

Tree Style Tab WebExtension

Tree Style Tab 2.0 tries to migrate old configuration and tree data automatically on the next startup of the browser according to the options.

Firefox users who upgrade Tree Style Tab to version 2.0, the WebExtension version of the add-on, will notice that tabs are displayed on the side just like in previous versions, but that the tab bar of the browser is not hidden anymore.

The reason for that is simple: the API is not there yet which enables extensions to hide the tabstrip of the browser. You can follow progress on the bug on Bugzilla@Mozilla.

Firefox users who want to hide the tab bar at this point in time may add the following line to the userChrome.css file in the /chrome/ directory of the Firefox profile to do so:

#tabbrowser-tabs { visibility: collapse !important; }

You need to remove the line again if you want to display the tab bar in Firefox at a later point in time.  The keyboard shortcut F1 toggles the sidebar on and off.

Tree Style Tab displays all tabs in the sidebar when you install the WebExtension version or upgrade to it. Relations between tabs are indicated by indenting tabs that are opened from the selected tab.

The extension ships with a great number of options that you control on about:addons. Options are divided into groups such as appearance, new tabs behavior, tree behavior or advanced.

You may use them to switch the Tree Style Tab sidebar to the right side, and change its theme, define how and where new tabs are opened after installation, and whether trees are collapsed automatically when new trees are created.

Closing Words

The release of the WebExtensions version of Tree Style Tabs guarantees compatibility with Firefox 57 and beyond. That's good news for existing users of the extension

Author Rating
3.5 based on 21 votes
Software Name
Tree Style Tab
Software Category
Landing Page

Tutorials & Tips

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  1. owl said on September 15, 2018 at 4:53 am

    “It is useless!”
    It is useless that the majority of postings (Comments) are.
    Constructive, fair, it should be the Comment on the basis of the demonstration.
    Without decent verification, attitudes to evaluate with personal preferences and fixed ideas are no different from hate speech.
    It is fascism, an egoistic point of view.
    These comments are ridiculing users and developers, and they are extremely poor (vulgar).
    Nonsense posts are “barren”. They “can not obtain empathy, only buy antipathy”

    At first I could not understand the significance of the existence of a hierarchical tree style tab.
    However, in Firefox it is “popular from a long time ago”
    Even CommunityForum at Vivaldi and Brave, the Request of the tree style tab is always talked about.
    Therefore, a motive for “trial” was born …
    Now, tree style tab is “essential functions”, but its presence is enough to “influence the evaluation of the Browser”.

    Its advantages:
    · Because the tab becomes Sidebar display style, you can easily identify the title (page name, topic name) of the tab.
    · Since the Tree is generated for each hierarchy, the parent tab> and children tab> grandson of the tab> …, regularity (correlation) is clear.
    · Since it becomes Suspend except for the Active tab, even if the number of tabs increases, the increase in RAM value can be suppressed.
    · Above all, favorite advantages:
    Since it is possible to use it like Net Surfing,
    In sites where many links are attached like ‘’ it is possible to open links one after another,
    In the case of web search that requires objective and multifaceted information gathering, you can also compare and browse them.
    In the general “Go back one page”, corresponding actions are necessary, so you can not move (return) immediately.
    A history for that becomes necessary, and since history is accumulated in WebStorage (DOM Storage) and Cache, RAM is necessary, and risk is also generated from Finger Printing.
    Bookmarks require time and labor to manage and search,
    Eventually, it will enlarge with a useless archive and get into great confusion.
    The point is, it depends on how to use.
    How to use and purpose of Browser has infinite diversity.
    Your values are not everything.

  2. klaas said on September 5, 2018 at 12:58 pm

    To hide the tabs at the top, use this css rule:

    @namespace url(“”);

    /* to hide the native tabs */
    #TabsToolbar {
    visibility: collapse;

    /* to hide the sidebar header */
    #sidebar-header {
    visibility: collapse;


    It works on Firefox Quantum.

  3. Laura Monteros said on January 6, 2018 at 8:23 pm

    It would be nice if it worked. I tried three of the new tree tab add-ons. They all worked on initial installation, but not after closing and reopening the browser or rebooting my PC and not after disabling and reenabling. I only enabled one at a time so there would be no conflict. Firefox Quantum is a mess. The main reason to use Firefox–add-ons–is gone.

  4. Teun said on December 7, 2017 at 8:42 pm

    Curious, I can’t find a chrome directory and/or userChrome.css file…
    (Kubuntu 17.10)

    As a matter of fact there is not a single css file in the Mozilla tree.
    Creating them did not help either.

  5. Robin said on December 5, 2017 at 1:46 am

    To all the fascists who tell us that if you have more than 10 tabs open, you have a problem:
    1-fuck you
    2-YOU are the one who has a problem here
    3-if you are not happy with something, that’s your problem. Don’t bother others with it and go to the psycholog to discover why you are frustrated
    4-shut up, we are working here and you disturb
    5-do you think you have the only truth?

    the list is long, shall I continue to please your dumb ass ego?

  6. Dan82 said on October 12, 2017 at 10:18 pm

    I struggled for months with the future of my browsing habits and usage scenarios. After a lot of reflection I have come to the conclusion that Tree Style Tab is probably the best of a bad lot. That’s true in my case at least, because I presently use many Tab Mix Plus features that will fall by the wayside once WebExtensions are the sole method of adding extra functionality to the browser.

    Of course there will be performance issues for power users, but also re-learning how to use the browser in a different manner will be challenging. In the face of other alternatives however, I see little choice. In my long quest for a proper alternative over these past months, I have often flirted with forks that retain a certain functionality, but that’s all it was, since I ended up back with the regular Firefox every single time. Whether it was SeaMonkey, Pale Moon, Waterfox or even some WebKit/Blink forks with a broader feature-set like Cent Browser, they all have the same issues in that they are maintained by either a single person or a very small team that does not get paid. While they should be admired for their enthusiasm and ideology, the cold hard truth is that all Firefox forks will have an increasingly difficult time of it as the development of the main branch progresses and large parts of the legacy code sees no active development anymore. It’s not that big an issue to hold out until early May 2018, since that is when support for the current ESR branch will stop. Beyond that I believe it to be impossible to use any traditional Firefox fork in a reasonable and secure manner. While the 52 ESR is indeed the best way to delay things until a proper alternative can be found, as a power user it is also a not inconsiderable compromise to miss out on the significant performance improvements that have been made from version 55 onward.

    But in the face of that, why stay with Firefox and why start using TST (for now)? As much as it offers less than excellent performance for power users with lots of tabs as I already alluded to earlier, the extension is still far superior to anything available in any WebKit/Blink based browser where tab management has always been THE most neglected feature. Combine that with the excellent container tabs (or “Multi-Account Containers” as the former Test Pilot extension is now called) integration and a handful of other natural advantages of the tree-based tab system – I’m mostly thinking about the natural grouping and collapsing functionality – and TST will be at the top of a very short list of options for stranded power users like me.

    For now, that is. My long-term hope is Vivaldi, a browser geared toward people that want and need more from a browser than Chrome is able to give them, a browser that takes inspiration from the old Opera which has been an excellent piece of niche software. Next to some truly great features introduced in a browser, there have also been some with a touch of whimsy to it. In the end however, I haven’t yet found a WebKit/Blink based browser that’s capable of handling and dealing with more than a dozen tabs without compromising usability. Not even Vivaldi, but it may just be the one to get there first and when that happens, I can finally say good-bye to Firefox, which is making a lot of noise and effort to align itself functionally with the market leader Chrome. Yeah, I can be honest about it and admit that it’s not their intention, but the result speaks for itself.

    1. Clairvaux said on October 12, 2017 at 11:32 pm


      How do you toggle between tree-style tabs and normal tabs ? I hope this is possible without getting in the Options menu. The F1 key is not doing anything on my setup, also I don’t see how to display the Tree Style Icon in the Firefox interface, also I don’t see the difference between what the two are supposed to do.

      I do wish developers would put the answers to such basic questions upfront in the software itself, before starting to add all sorts of high-faluting options.

  7. SCchmurtz said on October 2, 2017 at 11:07 am

    Your screen is in 16:9 and all the website are in vertical mode… So this feature should be by default in all navigators.

    There was tab center from mozilla himself few month ago….
    And now it’s gone, that’s a shame…

    There was tabkit 2nd edition which was awesome, I use it since many years, the functionalities are numerous and the colors and wheel scrolling in tabs are awesome.

    Now there’s tree style tab , great but I’m really looking for tabs colors (to group a context of search for example).

    I ‘m really zero with the new versions of firefox (Currently I use Palemoon) but this beta 57 is really fast. What is the path of userChrome.css ?
    Or where should I copy this file ?

  8. Anonymous said on September 27, 2017 at 2:26 pm

    Here is how you can test out userChrome.css changes in just a few clicks.

    If you don’t use Firefox beta or Nightly, you can open the Browser Toolbox with CTRL+ALT+SHIFT+I after you enabled the two checkboxes. (The panel where these boxes are can be opened by pressing F12)

    All changes made this way are temporary.

  9. Anonymous said on September 27, 2017 at 12:36 pm

    Great news. On top of hiding the tab bar, you can also have the sidebar hide and show with :

    Which was a TST feature that could be enabled but was disabled by default. TST’s author doesn’t want to put this feature in even if it becomes possible, he thinks hiding the sidebar is a task for another add-on. Meanwhile, userChrome.css to the rescue.

  10. Omar said on September 27, 2017 at 9:33 am

    Can i install firefox 57 beta within sandboxie to try it or it is not possible , and concerning noscript addon may it be available later ? . Thank you .

    1. Anonymous said on September 27, 2017 at 12:30 pm

      Yes NoScript will be available by Firefox 57’s release, so in about 6 weeks at most. uMatrix is nice too, blocks scripts, but it’s not quite the same as NoScript. If you really want to try out Firefox 57 beta you can switch to uMatrix for that profile though, should be good enough for six weeks depending on the reason you used NS in the first place.

    2. ay said on September 27, 2017 at 11:26 am

      why not just use umatrix, its much better than noscript once you get used to the interface.

      1. Anonymous said on September 27, 2017 at 1:11 pm
      2. Omar said on September 27, 2017 at 12:56 pm

        “umatrix” This add-on is not compatible with your version of firefox ( 57 ) .

  11. Gostas said on September 27, 2017 at 8:57 am

    You guys are prisoners of your own mind that thinks only of useless add-ons. gg

    1. Michael Rose said on October 5, 2017 at 10:19 pm

      I normally have between 10 and 30 tabs open. Vertical tabs are useful because most peoples monitors have far more useless horizontal space than vertical and hierarchies are a useful tool to organize even a modest number of tabs.

      In short your opinion is nonsensical.

      1. Teun said on November 17, 2017 at 3:27 am

        I have many tabs open, the usual ones like a couple of news sites and Slashdot, the weather in two places, and mostly for items I’m bidding on via an auction site, each kind with their own tree.
        Because these days all screens are wide screen it is logic to put the tabs on the left side.

    2. Anonymous said on September 27, 2017 at 12:25 pm

      Well argued man, well argued, now I’m convinced hierarchies of tab is a shitty feature

      1. said on October 2, 2017 at 1:01 am

        >Let’s be honest: people with, say, 100+ tabs open or more that 3 levels of tab nesting have problems: attention deficiency, procrastination, hoarding, fear of missing out, whatever.

        @Elias, don’t forget laziness. Or sloth if you prefer.

        People who want to keep 100+ tabs open, that’s their perogative. But don’t come on here and whine when the browser crashes and you can’t get them back. I have 0 sympathy for you. Zilch…

      2. My Name said on September 29, 2017 at 2:44 pm


        >people with, say, 100+ tabs open bla-bla-bla
        Stop generalizing.

        >I know because I have all of those
        So speak for yourself only, retard.

      3. Jojo said on September 28, 2017 at 7:42 pm

        @Clairvaux – I run Win10 Pro. I DO reboot periodically, maybe every 7-10 days generally. The OS is really stable compared to past Windows instances.

        I shut down my browsers when I go to sleep at night, otherwise they run all the day.

        I have 16GB ram and w/FF ESR, don’t have any real memory problems from the browser.

      4. Clairvaux said on September 28, 2017 at 1:53 pm

        @ Jojo

        Interesting. I use TMP too, but not to such an extent. What is your OS ? Does it never give you trouble for lack of rebooting ?

      5. Jojo said on September 28, 2017 at 9:55 am

        @Clairvaux, @Rick A. – I use TabMix Plus (TMP). I currently have 50 tabs open in FF ESR and 61 open in Pale Moon.

        I keep many tabs open as they are a type of intermediate storage for me. They are to-do action items but not generally ready to be promoted to permanent bookmarks. By being in my face, they force me to follow-up, whereas if I put something in bookmarks, I generally forget to look at it again.

        With TMP, I have a custom button that hides the whole tab bar and gives me all the screen space back.

        And no, I never shut my computer down. It is running 24 X 365 (24 X 366 in leap years).

        Now the problem with TMP is that the developer has been whining about not wanting to learn web extensions and unsure if he will re-develop TMP. If he gives up the ghost, then I might need to look at Tree Style Tabs or another solution.

      6. Rick A. said on September 28, 2017 at 5:19 am

        @Clairvaux – lol, i cannot understand to this day what 100+ Tabs accomplish. i guess my bookmarks accomplishes what their tab hoarding does, not insulting any tab hoarders by the way…..

      7. Clairvaux said on September 27, 2017 at 10:45 pm

        I am curious : what is the logic of having a huge number of tabs open (such as 100) ? I’m not trying to argue, I would just like to know how people use them, why they find this useful. Is it a substitute for bookmarks ? Are those people who never shut off their computers ?

      8. Anonymous said on September 27, 2017 at 3:31 pm

        Tree hierarchy from TST allows you to set up concurrent searches or browsing topics by theme, without having to manage or move tabs around. It works good with under 20 tabs which you will all close by the end of the day, no need for 50+ tabs to take advantage of it.

        Having several windows is messy IMO. To each their own use cases.

      9. Elias Fotinis said on September 27, 2017 at 2:10 pm

        It’s not an inherently bad addon, just a popular one that caters to a part of the userbase that some of us simply cannot related to. I have two monitors and 6 virtual desktops. I occasionally open 2-3 browser windows per desktop with perhaps 3-4 tabs each. I don’t need to go deeper, this isn’t Inception. I’ve used Panorama in Firefox and tab stacks back in good-old Opera, but I always found that they hindered rather than increase productivity.

        Let’s be honest: people with, say, 100+ tabs open or more that 3 levels of tab nesting have problems: attention deficiency, procrastination, hoarding, fear of missing out, whatever. I know because I have all of those. :/ However, I’m trying to improve myself by staying focused, simplifying my workflow and doing what actually matters. Less is sometimes more.

    3. Your Name said on September 27, 2017 at 11:45 am

      useless… yea.. sure dude, whatever..

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