Mozilla has put into circulation Firefox 146A new version of the browser arrives packed with small changes aimed at refining the daily experience rather than introducing major overhauls. The official launch will take place in a few hours, and you can read about its new features at [link to relevant website]. this linkIt coincides with the end of the year and is published along with the updates. Firefox 140.6 ESR y Firefox 115.31.0 ESRdesigned for environments that prioritize long-term stability.
This time, the focus is divided between Image quality improvements, new backup options, more accessible experimental features, and new features for developersMany of the changes are especially noticeable in Europe, both due to the arrival of new widgets and specific adjustments to the address bar for users in certain countries.
Firefox 146 introduces native fractional scaling on Wayland: a breath of fresh air for the Linux desktop
The most talked-about new feature is the support. native fractional scaling display support on Linux under WaylandUntil now, many users with 4K monitors or other high-density displays saw parts of the Firefox interface appear too large, blurry, or misaligned when using scaling factors such as 125% or 150% in GNOME or KDE.
With Firefox 146, the browser It correctly reads the display metrics provided by GNOME/GTK and the Wayland compositor.avoiding having to resort to workarounds using XWayland or manual adjustments in about:configThis results in texts, icons, menus, cursors, and web elements being displayed with greater clarity and at a size consistent with the rest of the desktop.
Mozilla indicates that this change makes the representation be more effectiveThis reduces problems where the browser worked internally at whole-scale resolutions and then rescaled the image, resulting in a loss of clarity. For those who use Linux as their primary operating system, especially on high-resolution laptops, this represents a significant improvement over previous versions.
Even so, the organization admits that there may be borderline cases with giant cursors, misplaced icons, or poorly positioned pop-upsIn these situations, the community is encouraged to report bugs so they can be fixed in future updates, something especially relevant for European companies deploying Linux desktops with Wayland in their fleets.
Firefox Labs for everyone and new AI-powered features
Firefox 146 extends access to Firefox Labs, the space from which Mozilla tests experimental features. Starting with this version, users can activate these functions without needing to participate in studies or send telemetry, something that until now was a common requirement.
The Labs panel is located in Settings > Experimental features or by writing directly about:preferences#experimental in the address bar. At launch there is three active experiments, among them the New Tab Widgets, which were temporarily paused due to a bug in the lists widget but have now been fixed.
Another of the version's major features is a system of AI-powered link previewWhen you hover your mouse over or interact with certain links, Firefox may Read the beginning of the linked page and generate a summary with the key points.This allows the user to decide more quickly whether it's worth opening. Information is handled with privacy in mind, using local processing whenever possible and avoiding unnecessary data transmission.
This type of tool opens the door to new ways of browsing and searching for informationThis is especially useful for students, journalists, or professionals who consult many sources. Mozilla's approach seeks to integrate artificial intelligence without turning the browser into a platform for massive data collection, something that could set it apart from other, more aggressive browsers in this area.
New features for Windows users: backups and graphical changes
In the case of Windows, Firefox 146 incorporates a feature of Data backup in Windows 10From the browser settings, users can create backups that include passwords, bookmarks, browsing history, and other profile dataThese backups are performed daily, stored locally, and can be password protected.
To use this feature, you need to Log in with Firefox Syncsince the system relies on that infrastructure to manage restores between devices. Although for now the creation of backups is limited to Windows 10, Mozilla points out that Support for other operating systems will come later.In Windows 11, the current version can restore a backup but cannot yet create one directly.
In the graphics section, the update Windows removes support for Direct2DUsers who rely on this technology have the alternative of remaining on the branches Firefox ESR 140.0 or higherIn addition, a bug that prevented Select tabs when the window was maximized and the cursor was at the top of the screen, a problem that affected certain monitor combinations.
macOS improvements: dedicated graphics processing and greater stability
macOS users receive a Firefox 146 update dedicated GPU process enabled by defaultThis process encompasses the implementation of technologies such as WebGPU, WebGL and the WebRender rendering engine, with the aim of isolating graphical errors from the rest of the browser.
In practice, if a serious failure occurs in the graphics code, The GPU process restarts transparently Instead of dragging the entire application down and causing a complete shutdown, this separation should reduce unexpected crashes, especially on pages with 3D content, web games, or applications that make heavy use of hardware acceleration.
This approach fits with Mozilla's strategy of Decompose Firefox into multiple specialized processesThis improves both overall performance and security. For those who use macOS in creative or development environments, the changes aim to provide a more robust experience during long sessions.
Interface and accessibility: color scheme and developer panel
Visually, Firefox 146 updates the Colors dialog in the settingswith a clearer color picker and swatches displayed next to each label. The goal is for users better understand which option they are adjusting and how it affects the browser's appearanceThis makes it easier to adapt Firefox to different accessibility needs and personal preferences.
The Inspector, one of the integrated development tools, is also receiving changes: now Hides unused custom CSS properties by default in the rules view. This decision pursues two goals: reduce visual clutter by reviewing complex styles and improving performance when rendering the panel, especially on pages with very extensive stylesheets.
New features for web developers and system administrators
Firefox 146 incorporates a number of changes geared towards web developers and those working with real-time applications. Of particular note is the ability to Sending post-quantum keys (PQ) during DTLS 1.3 handshakes over WebRTC connectionsThis step, still in its early stages, aims to strengthen the security of audio and video communications against future threats associated with quantum computing.
In the cryptographic field, the browser now supports compressed points of elliptic curves in WebCryptoThis expands compatibility with certain libraries and protocols that use this key format. This improvement is relevant for services that make intensive use of modern encryption and seek to reduce the size of transmitted keys.
Within the style engine, the new version adds support for the CSS function contrast-color(), that It receives one color and returns another of suitable contrast.Designed to automatically generate more readable text and background combinations, Mozilla notes that, for now, the behavior focuses on returning basic white or black variants, a useful first step toward ensuring minimum accessibility standards.
Support is also added to the property text-decoration-trimwhich allows the authors adjust the start and end points of the decorative lines (such as underlines) to better align them with the content. It is complemented by the property text-decoration-inset and with the arrival of menstruation @scopewhich makes it easier to restrict CSS styles to specific subtrees of the DOMsimplifying the maintenance of large codebases.
As for the graphics engine, Firefox integrates a updated version of the Skia librarywith performance and compatibility improvements. This, combined with the refinement of WebRender, aims to Smoother animations, smoother movement, and lower energy consumption, something key in laptops and mobile devices.
Legacy keyword support and new capabilities
To improve compatibility with existing sites, Firefox 146 adds support for the legacy keyword -webkit-fill-available as a value of width y heightMany web projects still rely on this term from the era when prefixes became widespread. -webkit-so its support helps to The pages will be displayed in a more predictable way without forcing the authors to rewrite code immediately.
Mozilla explains that this value acts in practice as alias of the standardized term stretchThis allows developers to move towards modern syntax without breaking the design in browsers that still expect the older variant. This duality is in addition to other adjustments that seek to balance adherence to standards with the realities of the legacy web.
Performance, security, and bug fixes in Firefox 146
Internally, the release notes mention a series of security patches and stability fixes These updates address vulnerabilities discovered since the last update. While many of these changes are not visible to the end user, they are part of Mozilla's rapid release cycle, which keeps the browser up-to-date against new threats.
Informal tests performed in high-resolution Linux environments suggest lower CPU usage during scrolling and zoomingpresumably thanks to the finer integration with Wayland and the adjustments in WebRender. Other improvements have also been observed. Slightly faster loading times on complex sites, accumulating incremental improvements introduced in previous versions.
Regarding the AI-powered link preview function, the analyses performed indicate that the impact on performance is reducedThis is essential for the feature to be perceived as helpful rather than a burden. Overall, the changes reinforce the idea of ​​a browser that evolves gradually, without major disruptions but with constant improvements.
Firefox availability and update
Mozilla plans Officially release Firefox 146 on December 9, 2025but the final binaries can now be downloaded from the Mozilla serversVersions are available for 64-bit, 32-bit and ARM64 systemsas well as the source code for those who prefer to compile the browser on their own distribution.
In distributions like Ubuntu, the version that reaches most users is the one packaged as Official Snap, That updates in the background and it installs automatically when the new version is ready, requiring only a browser restart to complete the process. Those using Flatpak or the package .deb Users will receive the update from the Mozilla APT repository through their usual package manager.
Linux Mint users can upgrade to Firefox 146 using the Mint Update tool from December 9, 2025, as the distribution maintains a package .deb It's synchronized with Mozilla's releases. For those who prefer a distribution-independent option, the [other option] is always available. Generic binary for Linux from the official website.
In the Windows and macOS ecosystem, the update is distributed via the integrated automatic update mechanismwhich downloads the new files in the background. Users only need to restart the browser when prompted to apply the changes, without needing to download anything manually.
Firefox 146 is presented as a polish version that addresses very specific problems: Clarity on Linux desktops with Wayland, data management and backups in Windows, graphical stability in macOS, usability in Android, and productivity for developers and advanced usersWithout any major fanfare, the update addresses long-standing weaknesses and lays the groundwork for upcoming features Mozilla has on the horizon, such as new tab widgets, more comprehensive AI tools, and design changes that will continue to arrive in future versions.