Mozilla has released Firefox 147, featuring support for the Freedesktop.org XDG Base Directory Specification that resolves a 20-year-old Linux issue. The update includes improvements for AMD GPU video playback, automatic Picture-in-Picture for videos, and enhanced security protocols. Available now for download, it marks the first major browser update of 2026.
Firefox 147 arrived on January 12, 2026, ahead of its official unveiling the following day, bringing several key enhancements primarily focused on Linux compatibility, performance, and web standards.
A standout change for Linux users is the implementation of the XDG Base Directory Specification, which standardizes file locations for new installations and profiles. Configuration files now reside in ~/.config/mozilla, data in ~/.local/share/mozilla, and cache in ~/.cache/mozilla, promoting a tidier system structure and easier backups. This addresses a longstanding bug dating back 20 years. Additionally, on GNOME desktops using the Mutter compositor, Firefox 147 adjusts window and rendering surface sizes to align with the pixel grid, ensuring sharper content rendering on displays with fractional scaling, regardless of window size.
Performance gains include zero-copy hardware-decoded video playback for AMD GPUs, achieving parity with Intel and NVIDIA hardware and potentially boosting video playback speed. The browser also introduces support for Compression Dictionaries per IETF RFC 9842, which can reduce bytes transferred for page loads, benefiting users on low-bandwidth connections.
User experience improvements feature the stabilization of automatic Picture-in-Picture (PiP), where videos in backgrounded tabs open in a PiP window by default; this can be toggled in Settings under Browsing. Tabs preferences have been reorganized into Opening, Interaction, and Closing categories for easier navigation, and a new Profiles section under General settings aids in managing separate browsing environments for work, personal use, or multiple users.
Security updates adopt the Safe Browsing V5 protocol, migrating from V4, and on Strict Enhanced Tracking Protection, Firefox prompts for local network access permissions. Language preferences in Accept-Language headers now use q=0.9 values, matching other browsers like Chrome to resolve compatibility issues.
For developers, additions include WebGPU support on Apple Silicon Macs, the Navigation API, ES modules in service workers, Brotli format in CompressionStream and DecompressionStream, CSS anchor positioning, and root-font-relative units like rcap and rch. Android users gain default Site Isolation for better protection against side-channel attacks such as Spectre, while Windows sees fixes for tab selection on certain monitors.
Experimental features persist, such as improved split tabs usability and customizable keyboard shortcuts via about:keyboard. Firefox 147 is available for Windows, macOS, Linux, and Android from Mozilla's website or FTP, with Linux distributions updating via snaps, flatpaks, or repositories.
