Almost a month after releasing version 137, Mozilla has launched Firefox 138, the latest update to its popular open-source web browser, now available for download.
The release’s main highlight is security, specifically targeting the browser’s Android version. Until now, users who needed mutual TLS authentication had to rely on desktop or specialized mobile apps. Firefox 138 changes this by adding full support for TLS client-authentication certificates on Android.
For tablet owners, web apps often appear as if they were still designed for a five-inch phone. Firefox’s “Desktop Mode” fixes that by sending a desktop-class user-agent string, preventing mobile layouts from stretching awkwardly.
From 138 onward, Desktop Mode was enabled by default on Android tablets, though power users could still toggle it off in Site Settings.
There are also several quality-of-life tweaks across desktop platforms that the new version brings to the table:
- Copy background tab links without switching contexts (macOS & Linux). A new tab-strip context-menu option lets users copy the URL of any background tab with a single click.
- Acrylic-style pop-up menus on Windows 11. Following the operating system’s Fluent Design guidelines, Firefox now paints its pop-up menus with the same semi-transparent acrylic blur found across native apps.
- Enhanced sharing from the Downloads panel (Android). File downloads in Firefox Mobile no longer feel like dead ends: you can share either the file itself or its original URL directly from the Downloads screen.
It’s worth noting also that Mozilla’s accessibility team has rededicated the former color-theme preferences into a unified “Contrast Control” setting. The move simplifies the mental model for users who rely on high-contrast palettes and aligns with WCAG guidance.
Lastly, the browser’s address- and credit-card autofill is now smarter about dynamic forms—reveals additional fields only after you pick a country or card type. Firefox will automatically populate those late-appearing inputs, trimming yet another slice of friction from online checkouts.
Those eager to immediately download the latest version of Firefox can do so directly from Mozilla’s server. Windows and macOS users can expect an over-the-air update within the next day. Users of rolling-release Linux distributions should look for Firefox 138 as an update in their repositories over the next few days.
