Mozilla published a new version of its open source browser Firefox today. Firefox 136 is a big update that ships with a few highly requested features.
Highlights include support for vertical tabs out of the box, a new Smartblock Embeds feature (more about that later), redesigned sidebar, and HTTPS-First policy.
Good to know: Firefox 128.8 ESR and 115.21 ESR are also available. These extended support releases focus on bug fixes and security updates.
Firefox 134: the major changes
Vertical Tabs
Love it or hate it. There seems to be little middle-ground when it comes to the position of tabs in browsers. One group likes the traditional horizontal layout for tabs, the other prefers them vertical.
Vertical tabs offer some advantages, especially on widescreen displays. More tabs and more of a page title can be displayed at the same time with vertical tabs. They do also pave the way for advanced organization features, such as hierarchic tabs that display in a tree-layout.
Firefox 136 users can give this a try with just a few clicks:
- Load about:preferences#general in the address bar. You may also click on Menu > Settings > General to get there.
- Scroll down until you come to the Browser Layout section.
- Check “Show sidebar”.
- Activate the settings icon at the bottom of the sidebar.
- Check “vertical tabs” to enable the feature.
Uncheck the option to return to horizontal tabs. The change is immediate and does not require a restart of the browser.
The equally long-awaited tab groups feature is not part of this release.
Firefox SmartBlock Embeds explained
SmartBlock is a privacy and security feature that is integrated into Firefox’s Enhanced Tracking Protection feature. Introduced in Firefox 87, the main goal was to address issues on webpages that were caused by the browser’s tracking protection feature.
The core idea is to replace the tracking script with wannabees. They act enough like the original to keep everything on the webpage intact, but do not compromise user privacy as nothing is reported.
The upgrade gives Firefox users options to unblock certain social media embeds that are blocked by Firefox in strict and private browsing modes. Mozilla says that support is limited at the moment but that additional embeds with be added in the future.
So, if you want to see a social media embed that is blocked by default, you can do so now in Firefox.
Other changes and fixes
- You can now also enable the new sidebar layout for Firefox to access various tools and features from the sidebar.
- Mozilla switched Firefox to a HTTPS-First model. Means, Firefox tries to upgrade any non-HTTPS page by default to HTTPS. If that fails, it will fall back to HTTP to allow the connection.
- Clear browsing data and cookies dialog now supports deleting saved form info,
- Firefox will move some background tabs on macOS to “lower power cores” to reduce energy usage.
- Hardware-accelerated HEVC playback is now supported on macOS.
- Firefox on Linux systems with AMD GPUs now has hardware video decoding enabled by default.
- Firefox is now available on ARM64 on Linux.
- The integrated weather forecasts supports Mexico, Brazil, Argentina, and Chile now.
- Address auto-fill is enabled for users in the UK.
Developer changes
- The autocorrect global attribute allows autocorrection in editable text elements.
- Intl.DurationFormat is now supported, enabling locale-sensitive formatting of durations.
- The Referer HTTP header is now sent in requests following a page refresh that redirects to a new page.
- The maximum size of Data URLs has been increased from 32MB to 512MB, matching the limit for Chromium browsers.
- A subset of the Cookie Store API has been implemented.
- WebRTC can now send and receive video encoded using the AV1 codec.
- WebRTC simulcast of screen-shared video with the H264 codec is also supported (AV1, H264, and VP8 can now be used for simulcast).
Enterprise changes
- Fixed Microsoft Entra SSO failing due to missing headers.
- New preference network.http.basic_http_auth.enabled allows admins to disable Basic HTTP authentication
- ExtensionSettings policy updated to allow extensions in private windows.
Security updates / fixes
Mozilla fixed a total of 15 security issues and bugs in Firefox. The aggregate severity rating is high and Mozilla makes no mentions of exploits in the wild. Some of the security issues are bugs that could have been exploited in the future.
You can check the full list of patches here.
Firefox 136.0 download and update
Mozilla Firefox 136 is available already. The ESR-versions are also available. Most Firefox installations should receive the updates automatically. Administrators who want the updates right away can force-check for them.
This is done by selecting Menu > Help > About Firefox in the browser. Firefox checks for updates and will install the latest version, if there is one.
Downloads are also provided on Mozilla’s official website.
Outlook
Firefox 137 is scheduled for a release on April 1, 2025. The two ESR versions, 115.22 and 128.9, will also be released on the day.
Additional information / resources
Closing Words
Mozilla is integrating features into Firefox that a vocal minority of users have requested for a long time. Now that vertical tabs are supported, it is tab groups that all eyes are set on.
What is your take on the direction that Mozilla is heading with Firefox? Leave a comment to join the discussion below.
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