Sidebar and Vertical Tabs Launch in Release 136
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03-10-2025 11:38 AM - edited 03-10-2025 11:43 AM
Hi folks! The updated sidebar and vertical tabs are now rolled out and available to all release users on Firefox 136.
How to enable it
Go to Firefox Settings → General → Browser Layout and check Show sidebar. Then, choose the settings icon in the sidebar to customize which tools appear. You can turn on vertical tabs from sidebar settings or simply right-click on the Firefox toolbar or tab strip and select Turn on Vertical Tabs.
Firefox Settings: Browser layout
Customize sidebar options
Key improvements
✅ Horizontal tab users can now hide and show the sidebar with one click using the sidebar toolbar button.
✅ Sidebar settings have been streamlined, making customization easier.
✅ Close vertical tabs in one click without expanding them. The close button now appears when hovering over a tab favicon.
✅ We’ve removed auto-collapse behavior of vertical tabs, as it proved cumbersome for many folks.
What’s next?
We’re working on more improvements to enhance the sidebar and vertical tabs experience. Some top priorities include:
- Remembering your last opened sidebar panel. When you hide the sidebar and then reopen it, the last opened panel will already be expanded. We hope to ship this as soon as Firefox 137 (April 1).
- More sorting options for history and better keyboard navigation, to match the functionality of the previous sidebar version.
- Expanding vertical tabs on hover for easier navigation.
As usual, we appreciate your patience and continued use as we refine these features and experiment to help us get to a better, more polished experience.
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04-02-2025 09:48 AM
The sidebar is a great idea--lots of web pages have so much space to the sides of the content, it sounded perfect. But while the horizontal sidebar has that little down-arrow-thingy to let you list all tabs, the vertical one does not! I went back to the horizontal one when I realized I could only see three non-pinned tabs and had no way to get the list of the rest of them to appear. Please fix this!!!!!
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04-02-2025 12:36 PM
I'd love to use the new feature, but I can't live without nesting tabs / tree structure
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04-02-2025 05:33 PM
There is a mysterious empty space on toolbar which can't be removed when I enable it. Most I can do is to move it the right side of address bar. This space is not present when I revert back to Horizontal tab.
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04-02-2025 11:09 PM
I know it might just be growing pains, but it takes me like 5-10 seconds every time to remember that I close tabs at the sides now, not at the top. I'd very much appreciate it if the address bar has a "close tab" button at the right of it, there's such a large space between the address bar and the "Save to Pocket" button, that a Close Tab button to the right of the address bar is a perfect place.
Also agree with others that too easy to accidentally close a tab now.
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04-03-2025 12:21 AM
I like the new sidebar but there is one option it's missing for me: please enable the rearangement of the tabs from top to bottom or bottom to top. Now the newest tab is always at the bottom and it feels very unintuitive. IMO the newest tab should always be on the top and the older ones at the bottom. Would be nice if there was an option to change this!
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04-05-2025 08:04 AM
I could see this being a nice option, good idea!
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04-03-2025 04:09 AM - edited 04-03-2025 06:29 AM
Version 138.0b2.
Please add "scroll to active tab". Lack of scrolling makes closing the current tab rather difficult.
EDIT: Turns out it scrolls to new tab, but if you expand/collapse the tabs it goes back to the top...
Drag and drop automatically created a new group. Could this be optional or a "do you want to" popup?
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04-03-2025 06:23 AM
Extremely embarrassing to see an AI feature. I fully disabled it from configs, and if you continue down this path, I will be looking for a new browser,
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04-05-2025 05:35 AM
Agreed. There's no world in which these bots are actually helpful. All they do is regurgitate and hallucinate.
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04-05-2025 08:06 AM
I simply didn't enable the feature, like so many other options I choose not to use. Is that not enough?
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04-03-2025 08:57 AM
Awesome, thanks for this. As a UX researcher & designer I would say it is necessary when displaying the bookmarks panel on the right AS WELL as the vertical tabs/sidebar that the bookmarks are on the left of the sidebar.
Conceptually , bookmarks are a more permanent/ universal resource than tabs which are (in theory) more temporal, so moving from left to right you have the permanent resource, the more temporary resource, and the active view.
Also, you open tabs from bookmarks, so you could think of it as : Permanent resource on left, apply to temporal resource on right-the tab is the heading for what you are looking at so it should be adjacent to the current view.
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04-03-2025 12:31 PM
I love the sidebar, but I found a little bug. Set the new sidebar to the right, opened ChatGPT to ask a about a technical issue, ChatGPT responded and added a YouTube video inside the sidebar, I clicked in the "Playing Picture in Picture" button, then the little PiP window opens but no video on it and close button didn't respond, had to end Firefox from task manager in order to close the PiP Window that got stock on screen.
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04-03-2025 08:29 PM - edited 04-03-2025 09:39 PM
I totally love this! Excellent idea. Hopefully you can add an option to put it on right vertical side of the screen. When launcher is on left side such as on Mac OS or Ubuntu, a confusion arises when hovering.
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04-04-2025 12:07 AM
Using the new sidebar limits us to having a very, very small area of the app window that we can use to actually move the window around, which is extremely inconvenient, especially for those of us with multiple screens that move stuff around. Right now I can only grab on to the tiny area between the back and forward arrows and the refresh button, and that just isn't enough. This kills the feature for me completely.
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04-04-2025 12:25 AM
Your screen might be very small. It's perfect here.
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04-04-2025 01:30 AM - edited 04-04-2025 01:32 AM
This is very nice! Thank you for the feature!
The one thing i don't like is that turning on vertical tabs changes how the sidebar is themed - using the names from Firefox Color, it changes from Toolbar Color to Background Color. This feels jarring and overwhelming with my theme, which uses the Windows accent color for the window decoration. I'd much rather the vertical tabs used the toolbar color palette.
On the plus side I want to add that I found it easy and intuitive to find the settings and customise the sidebar (but my "computer literacy" is rather high).
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04-04-2025 09:30 AM
I want to turn off AI. I see several comments here from other Mozilla members asking how to do this. The way AI is being developed and foisted down everyone's throat is more than merely "problematic". It is scary and dangerous. The actual developers of AI have been warning that AI is dangerous. We have opened Pandora's Box at a time of such political instability, with the rise of various Totalitarian, Authoritarian, Oligarchic tendencies gaining power all over the world. AI will be a terrible weapon in the hands of these groups, no? I don't want it on my beautiful Firefox Browser. I should be able to choose.
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04-04-2025 11:00 AM
I'm really enjoying this new feature so far, however there are couple improvements that would significantly improve the experience:
- Add a loading indicator/animation to the URL bar in addition to the one on the sidebar tab.
- Add the ability to hide extensions, either individual or all, from the sidebar.
- Add the ability to hide the "Customize sidebar" button.
- Add a search box at the top (when expanded) that will live filter tabs based on title, and a keyboard shortcut to move focus to that box similar to Ctrl+L.
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04-04-2025 11:18 AM
It'd be great if we had the option to choose if opening something like AI chatbot from the sidebar would change the width of the website or would be like a popup.
I saw something about tab groups in news about Firefox, I think, but couldn't create one in vertical tab mode (I haven't tried it in horizontal tab mode)
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04-04-2025 11:49 AM
How about the ability to pin certain tabs that are used regularly to the vertical sidebar and allow horizontal tabs for less used sites but actively working on them?
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04-04-2025 01:01 PM
OMG! I love vertical tabs. Previously tried to use TreeStyleTab but it took quite a lot of space in the end (so I used multiple windows as a "grouping" mechanism instead) but having collapsed sidebar with only icons is brilliant! I still use multiple windows but icons, most of the time, are more than enough to get to the desired website.
There is an issue with dragging-them out if the sidebar is on the right.
Would be nice to be able to add custom websites/panels to the bottom side of the window (maybe a good place for "pinned tabs"?
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04-04-2025 09:20 PM
Maybe I just can't find the setting, but I recently added the left sidebar to my browser, and I really like it! However, I think it would be perfect if my bookmarks weren't hidden in another context menu. I would prefer if they replaced the star icon with all of them visible.
If its not currently possible, I'm not sure why the dev team didn't consider this, because it currently adds one extra click; something that we don't have to do with bookmarks on the horizontal bar.
Would be nice to have both options !
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04-04-2025 11:16 PM
The side bar should properly hide itself when firefox enter fullscreen mode (F11)
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04-05-2025 04:48 AM - edited 04-05-2025 05:41 AM
Why is there extra horizontal space before the url bar whenever I enable vertical tabs? I can't drag it away when customising, either; gives a 🚫 symbol. I can move it around, but I can't get rid of it. It gives no tooltip when I hover over it, so I can't even tell what it is. And "remove from toolbar" is also greyed out when I right click on it.
And it's only there when vertical tabs are enabled.
[Edit]
It appears to be there to ensure you have a place to grab to drag the window. So, understandable, I guess. I don't really need it though, since I got the bookmarks toolbar open below that, and the open space on that serves the same purpose. Anyway, I dragged it to the right side of my url bar now, and it's fairly unobtrusive there.
It could definitely do with some kind of feedback, though, like a hover-over tooltip in editing mode. In fact, the normal "flexible space" is also missing a tooltip in editing mode.
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04-05-2025 06:00 AM
I noticed your edit after I left my comment, so I wanted to thank you here for the clarification.
In this case, though, I just wish I had more control over how the flexible space scales -- and better communication, as you said. The massive gap in the toolbar it creates when the window is maximized (mine almost always is) is an eyesore to me, as it stands.
It does at least disappear when I turn on the title bar, I'm noticing now, but for the purposes that I'm trying out the vertical sidebar (more vertical screen space), the title bar just refills the screen real estate this sidebar freed up.
Hopefully we're given a little more customization/control in the future, although I do think what this new sidebar feature offers, over all, is really nice.
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04-08-2025 02:13 PM
If you want to disable the flexible space entirely, you can add this to your userChrome.css file
#vertical-spacer {
display: none !important;
}
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04-05-2025 05:36 AM
I'm giving it a try, and I definitely like it so far (it emphases vertical space, which is more valuable to me when I'm web-browsing), but I'm begging you to let me remove the seemingly compulsory "flexible space" filler from the toolbar. No matter how or where I try to drag-and-drop it away, it refuses to go anywhere but a different place on the toolbar. It's driving me nuts lol.
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04-05-2025 12:28 PM
Like others have mentioned, an optional tree layout would be great! Really helps with the productivity, and is otherwise pretty unobtrusive.
I'll be using Tree Style tabs for now, but having a built-in option to hide horizontal tabs is so much better than editing userchrome.css!
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04-06-2025 02:20 AM
Two big things for me:
- Shortcut to toggle between expanded & favicon only view of sidebar. I like the sidebar view when focusing on firefox as main thing, but it can take up too much screen real estate when split screening if I need to say, write something & reference a web page at the same time. I'm a keyboard user, so this is one of the few things I have to click on the UI for right now.
- Please unify the "sidebar extension" interface with the rest of the extension interface. i.e. I don't see why we can't be allowed to put any extension there, for example bitwarden displays identically between the sidebar extension and the normal extension in top right. As part of this, please let us control what extensions appear there. Right now I am stuck with a useless one with takes up a whole row of the sidebar, because devs created a sidebar ui for the app, in a time where it simply came up in a dropdown. So now this slightly legacy view is cluttering the new vertical tab view!
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04-07-2025 04:04 AM
I really like the vertical tabs feature. My only feedback is that when using vertical tabs, it becomes harder to move the Mozilla window around, since you have to find an empty space in the toolbar to drag it. Maybe if you make it possible to move the window by clicking and dragging at the very top—like it worked with horizontal tabs—it would solve the issue.
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04-07-2025 06:54 AM
Looks great in terms of streamlining the browser window. However, I'll wait to utilize until I can hide the tabs when I'm not using them. Bummer this option wasn't implemented from the start.
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04-07-2025 08:53 AM
I just received this update with vertical tabs, and I like the idea! However, I can't get my sidebar to look like the one in the original post by asafko. My vertical tabs won't collapse into an icon. The tabs always show the page title. I can drag to resize the sidebar, but the sidebar closes when I fit it to the icon size. Is this just me?
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04-07-2025 01:39 PM
My side bar has white icons on a light grey back ground.
When I activate the side tabs the fav's are in color but the text is white on the same light grey. I am in Dark Mode. How can I make the side bar background dark too?
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04-07-2025 07:53 PM
It would be great if this could be changed to be a "per window" setting instead of a global setting for all windows. I want horizontal tabs on my regular windows and vertical tabs on my media / youtube window. But as is, I have to pick or choose one for all windows.
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04-08-2025 03:17 AM
I'm stunned to find that there is no option to nest and group tabs like in Tree-style tabs Extension and in Edge. For me this is the best reason for having vertical tabs. I will now go back to using Tree-style tabs rather disappointed
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04-08-2025 06:33 AM
Asafco, Please give users an option to place browser tabs as the bottom line below menu/URL/bookmarks at the top of the page. That is, top down: menu, then URL, then bookmarks, then tabs.
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04-08-2025 02:30 PM
I'm using the new Firefox vertical sidebar and have noticed an inconsistent display of the bottom toolbar items. When all default items (History, Tabs, AI, Bookmarks, etc.) are enabled, they appear as distinct, easily clickable buttons. However, if I disable any of these items, the remaining enabled tools stack vertically like tabs, which is less efficient and visually unappealing. It seems that the toolbar items only appear as icons when they are considered to be overflowing.
In addition to the main issue, I'd like to suggest the following features to enhance the new vertical sidebar:
- Resizable Pinned Tab Section:
Allow users to drag and resize the section between pinned tabs and regular tabs when the sidebar is collapsed. This would eliminate the need for scrolling when many tabs are pinned. - Hover-to-Expand Sidebar:
Implement an option to automatically expand the collapsed sidebar on mouse hover. Provide an option to have the expanded sidebar float above the page content, rather than resizing the main window - Reorderable Bottom Tools:
Allow users to rearrange the order of the sidebar tools located at the bottom of the sidebar. - Sidebar Extension Selection:
Provide the ability to choose which sidebar extensions are displayed in the sidebar. - Toolbar/Sidebar Integration:
Explore integration between the toolbar and sidebar, allowing users to add any Firefox tool to either location. - URL Bar Drag Margin:
Add a small (approximately 2mm) margin at the top of the URL bar to facilitate window dragging. - Sidebar Tab Scrolling:
Allow the user to scroll on the sidebar to switch between tabs.
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04-09-2025 04:15 AM
Hi there!
The new sidebar feature with vertical tabs is a nice update, something that should have been done a long time ago! I've been using TreeStyleTabs for a long time, and the new vertical tabs logic in the sidebar conflicts with it. I'd prefer if TreeStyleTabs could simply replace the default vertical tabs logic in the sidebar. Right now, with TreeStyleTabs enabled, I get two sidebars with tabs, and I have to close the default vertical tabs because I don't need them. However, the ChatGPT button at the bottom is handy, so I’d like to keep it.
The issue is that pressing the ChatGPT button replaces TreeStyleTabs with the ChatGPT window and enables the default vertical tabs. As a result, I hide the sidebar with the default vertical tabs but lose the ChatGPT feature. Also, I’m glad the horizontal tabs are fully disabled, as they’re completely useless.
To summarize, I don’t know how you should implement this, but please make it possible to replace the default vertical tabs layout with TreeStyleTabs. Or, if that’s not feasible, make it easier to hide the sidebar with the default vertical tabs and prevent it from accidentally reappearing.
Thank you.
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04-10-2025 02:48 AM
The vertical tab is great, many thanks :).
But I am facing a problem. I have several tabs open and when the "expand sidebar on hover" is enabled, the scrollbar always go to the top, this makes navegation complicated. Keeping the sidebar present "solves" the problem, but would be nice to keep it close and have more space in the browser.
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04-10-2025 05:47 AM
Using Firefox 137.0 (64 bit) Win 11 24H2
I have just noticed that the background colour of the sidebar and the customise firefox is a pinkish red. I much prefer them to be white. I cannot see or find a way to change the pinkish red to white nor why this colour has been chosen.
I do have a theme which includes various tones of red. Not sure if this is relevant but if it is, it seems to defeat the concept of having a theme, which I regard as a header that should not affect the body of the page).
Thanks in advance for the help.

