Firefox 124 Update: PDF and Caret Browsing

Mozilla officially released Firefox 124 on March 19, 2024. While some browser updates focus purely on speed benchmarks or visual overhauls, version 124 targets specific usability gaps that have frustrated users for years. This update introduces critical improvements to how the browser handles PDF files and boosts accessibility through Caret Browsing. If you work with documents in your browser or require keyboard navigation tools, this release offers significant value.

Caret Browsing Comes to PDFs

The headline feature of Firefox 124 is the integration of Caret Browsing into the built-in PDF viewer. For many users, this term might be unfamiliar, but it is a vital tool for accessibility and power-user efficiency.

Caret Browsing mode allows you to navigate through a webpage or document using a text cursor, similar to how you navigate a Word document. You use the arrow keys on your keyboard to move through the text, select specific lines, and jump between paragraphs. Before version 124, this feature worked on standard HTML webpages but was disabled or clunky when a PDF was opened within the browser.

Why This Matters

For users who rely on screen readers or have motor impairments that make using a mouse difficult, the previous inability to use standard keyboard navigation inside a PDF was a major barrier. Firefox 124 removes this hurdle.

Even if you do not use assistive technology, Caret Browsing improves text selection. We have all struggled to highlight a specific sentence in a PDF using a mouse cursor, only to accidentally highlight the entire page or the wrong column. By pressing F7 to toggle Caret Browsing, you can use the Shift + Arrow keys to highlight exactly what you need with precision.

Android Improvements: Screen Wake Lock API

The desktop version was not the only recipient of upgrades. Firefox for Android received a substantial utility update in version 124 with the enablement of the Screen Wake Lock API.

This application programming interface (API) allows websites to request that your screen stay awake. This is incredibly useful for specific types of mobile browsing experiences:

  • Cooking: If you are following a recipe on a cooking blog, the screen will not dim or lock while your hands are covered in flour.
  • Reading Long Form: You can read long articles without constantly tapping the screen to keep the phone awake.
  • Presentations: If you are using a web-based presentation tool on a tablet or phone, the device ensures the display remains active.

Previously, this was a friction point for Firefox users on Android, forcing them to change their system-wide display settings just to read a long article. Now, the browser handles it intelligently on a site-by-site basis.

Platform-Specific Updates for Mac and Windows

Mozilla often includes tweaks that help the browser feel more “native” to the operating system you are using. Firefox 124 includes specific changes for both Windows and macOS users to streamline the user interface.

Windows: Jump List Efficiency

On Windows 10 and 11, the “Jump List” is the menu that appears when you right-click an icon on the taskbar. In Firefox 124, Mozilla optimized how the Jump List is populated. This results in a smoother experience when you are trying to quickly open a new private window, access a recent tab, or open a pinned site directly from the taskbar without maximizing the browser first.

macOS: Fullscreen API Integration

For Mac users, Firefox 124 now uses the native macOS fullscreen API for all fullscreen windows. While this sounds technical, the practical result is a better user experience for those who use “Spaces” or swipe gestures on their Macbooks. The browser now behaves exactly like other native Apple applications when entering or exiting full-screen mode, reducing visual glitches and improving transition smoothness.

Search Engine and Privacy Changes

Firefox is known for its stance on privacy, and version 124 expanded the availability of Qwant. Qwant is a privacy-focused search engine based in Europe that does not track user history.

With this update, Mozilla expanded Qwant availability to all languages in the France region, along with Belgium, Italy, the Netherlands, Spain, and Switzerland. This gives users in these regions a seamless way to switch away from Google or Bing without installing external extensions.

Security Patches and Under-the-Hood Fixes

No browser update is complete without security maintenance. Firefox 124 addressed several critical vulnerabilities found in previous versions. These included memory safety bugs that, if left unpatched, could theoretically allow malicious actors to execute code on a user’s computer.

Updating to version 124 (or the subsequent versions released since) patches these holes. Mozilla categorizes these fixes based on severity, and version 124 included fixes for issues labeled “High” severity. This reinforces the importance of not delaying the “Restart to Update” prompt when it appears.

How to Check Your Version

Since Firefox updates in the background, you may already be running version 124 or higher (such as version 125 or 126). To verify which version you have and ensure you have the PDF tools mentioned above:

  1. Click the Menu button (three horizontal lines) in the top right corner.
  2. Click Help.
  3. Select About Firefox.
  4. A window will open displaying your current version number. If an update is available, it will download automatically.

Frequently Asked Questions

How do I turn on Caret Browsing in Firefox?

You can toggle Caret Browsing on or off by pressing the F7 key on your keyboard. A dialog box will appear asking you to confirm that you want to enable the feature. Once active, a blinking cursor will appear within the text on the page or PDF.

Is Firefox 124 compatible with older extensions?

Generally, yes. Firefox operates on a stable extension architecture. Unless an extension has been abandoned by its developer for years, it should continue to function correctly with version 124.

Does the Screen Wake Lock work on iPhone (iOS)?

The specific Screen Wake Lock API update mentioned for version 124 was focused on Firefox for Android. iOS (iPhone/iPad) operates on Apple’s WebKit engine, which limits how third-party browsers like Firefox can interact with system hardware. Therefore, feature parity between Firefox Android and Firefox iOS is not always 1:1.

Why can’t I edit text in PDFs with Firefox 124?

It is important to distinguish between “Caret Browsing” and “PDF Editing.” Firefox 124 allows you to navigate and select text with a cursor (Caret Browsing). It also supports adding text overlays, drawings, and signatures. However, it is not a full PDF editor like Adobe Acrobat Pro; you cannot delete or rewrite the existing base text of a PDF document.

Is Firefox 124 faster than Chrome?

Speed tests vary based on hardware and the specific website being loaded. Firefox 124 remains highly competitive with Chrome. While Chrome may win in raw JavaScript processing speeds in some benchmarks, Firefox is often praised for better memory management, meaning it may slow down your computer less when you have dozens of tabs open.