What’s New and Improved in Firefox 137.0?

Mozilla released Firefox 137.0 on April 1, 2025, bringing a host of improvements aimed at enhancing both functionality and security for its users. Let’s take a closer look at what’s new in this version.

Tab Grouping for Better Organization

Firefox 137 introduces a tab grouping feature, allowing users to organize related tabs together. Simply drag one tab over another to create a group, assign it a name and color, and enjoy a more streamlined browsing experience. This is especially helpful for multitaskers or users working on multiple projects at once.

Smarter and More Intuitive Search Bar

The address bar (also used for search) now comes with several enhancements:

• Unified Search Button: Easily switch between search engines or modes.

• Search Term Persistence: Your typed queries remain visible, making it easier to edit or refine them.

• Context-Aware Search Suggestions: Firefox suggests making certain engines permanent if used frequently.

• Search Shortcuts: Use keywords like @bookmarks, @tabs, @history, and @actions for targeted searches.

Improved PDF Experience

Working with PDFs in Firefox just got easier:

• Automatic Link Detection: All links in PDF documents are now clickable by default.

• PDF Signing: You can now sign PDF documents directly in the browser and even save your signature for later use.

HEVC Video Support for Linux

Linux users can now enjoy native support for HEVC (High Efficiency Video Coding), providing better video quality and performance for compatible media.

Built-In Calculator in the Address Bar

Type any math expression into the address bar and Firefox will instantly show the result. You can also copy the result to your clipboard with a click.

Developer Tools Enhancements

Developers will appreciate the following updates:

• Font Panel Metadata: View font details like version, designer, vendor, and license.

• Network Panel: Now allows you to substitute server responses with local files for testing.

Web Platform Updates

Web developers can take advantage of new capabilities such as:

• SVG 2 Path API Support: Enables more complex and customizable SVG drawings.

• New CSS hyphenate-limit-chars Property: Gives more control over hyphenation behavior in text.

Security Fixes

Firefox 137 includes several critical security patches:

• Use-After-Free in XSLTProcessor: Fixed a vulnerability involving document transformations using JavaScript.

• JIT Optimization Bug: Resolved an issue where 32-bit values could be leaked from the stack during Just-In-Time compilation.

• File Handle Leak: Addressed a bug that could expose file descriptors from forked servers to web content processes.