Firefox 151 brings PDF merging, local profile backup, document PiP, and enhanced privacy

Mozilla has released Firefox 151, rolling out substantial updates for privacy, usability, and platform alignment on desktop and Android. Users can now merge multiple PDFs directly within the built-in PDF viewer, eliminating the need for external services. Local profile backups and restore functionality are now offered on macOS and Linux, allowing users to move profiles across systems. Following privacy enhancements, Firefox enforces prompts for website access to local network devices and applications for all users, a measure previously restricted to those using strict Enhanced Tracking Protection settings.

Building on privacy improvements, standard Enhanced Tracking Protection now limits browser fingerprinting attempts, while private browsing mode lets users erase session data instantly without shutting down the browser. On macOS, the universal clipboard works as expected when pasting URLs from iOS, and HTML select dropdown menus reflect native system styling.

Meanwhile, Firefox for Android introduces an AI Controls settings' section for managing AI-enhanced features and allows users to vertically swipe on the toolbar to view tabs. The Document Picture-in-Picture API is now supported, enabling always-on-top content popups. Extensions and themes persist when profiles are moved to new locations or operating systems. Additional updates include address autofill for users in the Netherlands, enhanced discoverability for the about:translations page, and on Windows, geolocation that respects the user's system location permissions.