Mozilla's Firefox 136 is out today. Despite recent Mozilla moves, it's still a better choice for the privacy-conscious than Chrome.

Firefox 136 is already on [1]Mozilla's FTP server and will start trickling out onto the main webserver later today. This version delivers three important features that will be good news for some users after the arguably bad news of [2]"do not track" being dropped from version 135 .

For this particular vulture, the most pleasing update is the long-awaited built-in support for vertical tabs. As we reported last year, [3]this was available in the beta of Firefox 131 but not in the final version.

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We wrote about vertical tab extensions in our [5]Firefox for power users guide in 2022. We needed to undo one of the customizations we described in that story to get the new vertical tab bar to display. It is the same toolbar as the old horizontal one, so we had to remove our custom stylesheet that hid the horizontal tab bar.

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As we described a few years ago, the stylesheet is called userchrome.css and lives inside a folder called chrome in your profile directory. We just moved the chrome folder one level up, into the main profiles directory, and restarted Firefox.

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Firefox 136 finally delivers a snazzy built-in vertical tab bar, along with other niceties – click to enlarge

The vertical tab bar has a couple of immediately apparent advantages over the add-ons: it can be resized down to just show the tabs' [9]favicons . This is smaller than most extensions can go, making it more space-efficient – a bonus for smaller screens. Additionally, the vertical tab bar is in addition to Firefox's integral sidebar, and it contains buttons to access several features of the stock sidebar, such as synchronized tabs, history, and bookmarks.

With the tab sidebar in its default position on the left, clicking these buttons reveals the existing sidebar to its right, closer to the webpage itself. It works really well; the integration is smooth and slick and works better than any of the vertical tab extensions we have used in the past.

There's also a new toolbar button, leftmost in the main browser toolbar, to toggle the vertical tab bar on or off, another bonus for small laptop screens. The list of tabs is flat and non-hierarchical, which is how this vulture prefers it – and also means that there's still a place for the classic [10]Tree Style Tabs (TST) extension. TST also powers the [11]vertical tabs in Waterfox , keeping that project ahead even as Mozilla catches up.

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Even if you're perfectly happy with horizontal tabs, we urge you to give this a go. It's worth any temporary disorientation: you can see lots more legible tabs vertically than you can horizontally, and it makes much better use of widescreen displays. It may take some time to adjust, but the effort is well worth it.

This isn't the only new feature worth having, though. From version 136, native Arm64 builds of Firefox for both Linux and Windows are available, which will run faster and use less battery power than running via x86 emulation. Firefox already supported Arm64 Macs, but version 136 is aware of Apple Silicon's asymmetric CPU cores and automatically moves some background tasks to efficiency cores, so it will use a little less battery power. There's also an optional sidebar with the now near-obligatory "AI" chatbot, but we're not interested in automated plagiarism systems and didn't try this.

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The new sidebar and toolbar layout works well on Linux, too. Handy on small lappies – click to enlarge

There are less visible improvements as well. Linux users with AMD GPUs now get hardware-assisted video decode, and Mac users get hardware-assisted playback of HEVC (H.265) video files. On any modern computer, this probably won't be noticeably smoother, but it should use less CPU and power. Mac users downloading a fresh copy of Firefox will find the download is a little smaller, thanks to LZMA-compressed .dmg files. When visiting a new site, this version first tries HTTPS. If that fails, instead of showing an error, it retries over unencrypted HTTP. For sites that don't load correctly, Android users can now report this directly from the app's main toolbar menu.

[14]Mozilla flamed by Firefox fans after promises to not sell their data go up in smoke

[15]CentOS Connect conference announces return of Firefox

[16]Firefox ditches Do Not Track because nobody was listening anyway

[17]Mozilla's Firefox browser turns 20. Does it still matter?

As well as these user-facing features, there are as always some [18]changes for web developers , too.

After the announcement of [19]Mozilla's new terms of use , we suspect many disappointed users will look elsewhere, but we feel Firefox – or one of its derivatives – remains the best browser option. As The Register [20]warned last month , this week's new version of Google Chrome disables uBlock Origin. In time, this change will likely make its way downstream to other Chromium-based browsers. One of those is Microsoft Edge, which has [21]started switching off uBlock Origin and other Manifest V2-based extensions. Brave is another Chromium browser but has its own ad blocking built-in.

One [22]remaining option for Chrome users is the less-capable [23]uBlock Origin Lite .

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The unrestricted [25]uBlock Origin still works fine in Firefox, as well as its various downstream browsers such as [26]LibreWolf – version 136 of which will no doubt appear soon. As before, [27]Waterfox remains based on the [28]ESR edition of Firefox – currently, that means [29]Firefox 128 . ®

Get our [30]Tech Resources



[1] https://ftp.mozilla.org/pub/firefox/releases/136.0/

[2] https://www.theregister.com/2024/12/12/firefox_do_not_track/

[3] https://www.theregister.com/2024/09/04/firefox_130_release/

[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2Z8eGDjK4FuHbq-6fef4oeAAAAMI&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0

[5] https://www.theregister.com/2022/09/26/firefox_power_user_guide/

[6] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44Z8eGDjK4FuHbq-6fef4oeAAAAMI&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0

[7] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33Z8eGDjK4FuHbq-6fef4oeAAAAMI&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0

[8] https://regmedia.co.uk/2025/03/04/ffox_136_mac.jpg

[9] https://www.w3schools.com/html/html_favicon.asp

[10] https://github.com/piroor/treestyletab

[11] https://www.waterfox.net/blog/waterfox-x-treestyletab/

[12] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44Z8eGDjK4FuHbq-6fef4oeAAAAMI&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0

[13] https://regmedia.co.uk/2025/03/04/ffox_136_ubuntu.jpg

[14] https://www.theregister.com/2025/03/02/mozilla_introduces_terms_of_use/

[15] https://www.theregister.com/2025/02/10/centos_firefox/

[16] https://www.theregister.com/2024/12/12/firefox_do_not_track/

[17] https://www.theregister.com/2024/11/13/mozillas_firefox_browser/

[18] https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/136#changes_for_web_developers

[19] https://www.theregister.com/2025/03/02/mozilla_introduces_terms_of_use/

[20] https://www.theregister.com/2025/02/24/google_v2_eol_v3_rollout/

[21] https://www.neowin.net/news/microsoft-begins-turning-off-ublock-origin-and-other-extensions-in-edge/

[22] https://www.theregister.com/2024/08/06/chrome_web_store_warns_end/

[23] https://github.com/uBlockOrigin/uBOL-home

[24] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33Z8eGDjK4FuHbq-6fef4oeAAAAMI&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0

[25] https://ublockorigin.com/

[26] https://librewolf.net/

[27] https://www.waterfox.net/

[28] https://support.mozilla.org/en-US/kb/choosing-firefox-update-channel

[29] https://www.theregister.com/2024/07/11/firefox_128_new_esr/

[30] https://whitepapers.theregister.com/