Mastering Firefox 151: A Complete Guide to the New Firefox Home and PDF Merging

Overview

Firefox 151, released on May 19, 2026, introduces a refined new tab experience and a highly anticipated PDF merging feature. This guide walks you through every change, from the redesigned Firefox Home page to the step-by-step process of combining PDFs directly in your browser. Whether you’re a daily user or a power user, these updates streamline your workflow and modernize the browsing interface.

Prerequisites

• Firefox 151 installed on your desktop (Windows, macOS, or Linux).
• An active internet connection for the initial update and for some PDF merging features (if using online templates).
• Basic familiarity with Firefox’s interface is helpful but not required.

Step-by-Step Instructions

1. Exploring the New Firefox Home Tab

Upon updating to version 151, you’ll notice the new tab page has a fresh name and subtle visual tweaks. Formerly just “New Tab,” it’s now called Firefox Home. The layout retains your Top Sites, Pocket stories, and recent activity, but with three key changes:

• Rounded Search Bar: The address/search bar now features a pill-shaped, rounded design (a precursor to the upcoming “Nova” redesign). It is no longer sticky; it scrolls with the page content.
• Updated Follow Button: The “Follow” button for topics now appears as a plus-sign icon (+) located to the left of the section header.
• Stories Stay: The Pocket-powered story grid remains unchanged in layout and behavior.

To see these changes in action:

1. Open a new tab (Ctrl+T or Cmd+T).
2. Observe the search bar: it is now pill-shaped and will disappear when you scroll down (no longer sticky). Type a query to test the rounded visuals.
3. Scroll down to the “Recommended by Pocket” section. Notice the “Follow” button next to topic headings has been replaced with a simple plus icon. Click it to follow that topic.

Tip: If you prefer the old look, you can still customize your new tab page via Settings > Home > Firefox Home Content to toggle sections on/off.

2. Merging Multiple PDFs in Firefox

Firefox 151 introduces a built-in PDF merging tool, eliminating the need for third-party services. You can combine two or more PDF files directly in the browser’s PDF viewer.

Access the Merging Tool

1. Open any PDF in Firefox by double-clicking it or dragging it into a tab.
2. Look for the new Merge PDF option in the toolbar (usually an icon with overlapping rectangles). If the toolbar isn’t visible, click the three-dot menu (…) in the top-right corner of the PDF viewer.
3. Select Merge PDF from the dropdown menu.

Add and Reorder PDFs

1. A new sidebar opens on the right. Click Add Files or drag and drop additional PDFs into the list.
2. You can reorder files by dragging their thumbnails up or down. The final PDF will combine them in the order displayed.
3. Optionally, click the gear icon to adjust settings like compression level or whether to include bookmarks.

Merge and Save

1. Once satisfied with the order and settings, click the Merge button at the bottom of the sidebar.
2. Firefox processes the files (progress bar appears) and then displays a preview of the merged PDF.
3. Click Download or Save to store the combined file locally.

Note: The merging happens entirely in your browser – no data is uploaded to external servers, ensuring privacy.

3. Other Notable Updates in Firefox 151

While the redesigned home tab and PDF merge are the headline features, version 151 also includes:

• Enhanced Security: Updates to certificate handling and DNS-over-HTTPS.
• Performance Tuning: Faster JavaScript execution and reduced memory usage when many tabs are open.
• Bug Fixes: Resolved issues with video playback and certain extensions.

Common Mistakes

• Not updating Firefox: Ensure you’re on version 151 by going to About Firefox (three-line menu > Help > About Firefox). If you don’t see the new features, restart the browser after updating.
• Missing the “Merge PDF” option: This feature only appears when a PDF is open. It is not available in the main toolbar – you must first open a PDF file.
• Expecting the old sticky search bar: The search bar is no longer sticky by design. If you want it to stay visible while scrolling, you may need to use a custom userChrome.css tweak (advanced).
• Overwriting original PDFs: When merging, the originals remain untouched. The merged file is a separate new file – make sure to choose a distinct name when saving.
• Using third-party merge tools unnecessarily: Many users attempt to merge PDFs via online services, but Firefox 151 now handles this natively and securely. Check the built-in tool first.

Summary

Firefox 151 brings two major quality-of-life improvements: a visually refreshed Firefox Home tab (with a rounded, non-sticky search bar and a revamped follow button) and a native PDF merging tool that keeps your data private. The guide above walks you through adapting to the new home page and combining PDFs in a few clicks. With these updates, Mozilla continues to blend aesthetics with functionality, making daily browsing smoother and more intuitive.

For related reading, see our guide on PDF merging or the new tab design sections above. If you encounter any issues, check the Common Mistakes section for quick fixes.