Firefox includes a built-in PDF viewer to display PDF files inside the browser window. This article explains how to use the built-in PDF viewer, how to fix the common issues you might encounter, and how to use another PDF viewer.

Use Firefox’s built-in PDF Viewer

Firefox's built-in PDF viewer allows you to view almost all PDF files found on the web without an external application (exceptions to this are PDF files with a MIME type incorrectly set). The built-in viewer is used when Portable Document Format (PDF) files are set to Open in Firefox in your Firefox settings for different types of files. This is the default setting. When you click a link to a PDF file or open it from the Firefox Downloads panel, it will be rendered with the built-in PDF viewer. (To learn more about the built-in viewer, see below.)

The built-in PDF viewer will open the PDF file in Firefox without saving it.

When you're viewing a PDF file in Firefox, you can use the download button in the PDF viewer's toolbar to download and save the PDF file to your computer.

Fill out forms in PDF Viewer

Some PDF files have interactive fields to fill in data (such as on forms). Using Firefox's built-in PDF viewer, you can fill out fields such as text, check boxes and radio buttons. After entering data into these fields, you can download the file to have the filled-out version saved to your computer.

View document thumbnails or outline: The slider button on the far left will open a sidebar with thumbnails of the document's pages. Some documents will also have an outline view available. These make it easy to navigate through a long document.
Page up and down or skip directly to a page: You can use the up and down arrows to page through a document or enter the number of the page you want to go to.
Change the size of the document: Use the + and − buttons to zoom in and out or choose a zoom setting from the dropdown menu.
Print: Click the Printer button to open the print setup dialog.
Download: Click the Download button to save the PDF file to your computer.

Annotate PDF files

Annotating a PDF allows you to add notes, highlights, and other markings directly on the document. This is especially useful for making corrections, highlighting important information, or adding personal notes for future reference.

Click to choose a color and text size before selecting where on the document you wish to add text.
Click to choose a color, thickness and opacity before then being able to draw on the document. Downloading the file saves a copy of the document with your annotations.

Highlight in PDF files

Add a highlight

To highlight text or an area in a PDF document, first select the desired text or area. Then, click on .
Choose your preferred highlight color and adjust the thickness of the highlight.

Show/hide all highlights

To manage the visibility of all highlights in a PDF file, first click at the top right of your screen.
Then, use the toggle located under the Show all option to either display or hide all the highlights in the PDF file.

Edit or delete a highlight

Click on the area you previously highlighted.
To change the color of your highlight, click on and select a new color.
To remove the highlight, click .

Add an image to PDF files

Starting in Firefox version 119, you will be able to add an image to a PDF file. This feature is being rolled out gradually, so it may not be available to you at this time.

In many PDF-related tasks, incorporating images can provide supplementary information to your content.

Inserting an image:

On the top right of the screen, click .
Click + Add image. This will prompt the file selection window.
Browse and select the desired image file to add it to the PDF.

Repositioning and resizing the image:

Drag and drop the image to your preferred location within the PDF.
To adjust the image size, click and drag its borders until it fits your desired dimensions.

Adding Alt Text for accessibility:

After adding the image, click + Alt text.
In the provided space, either:
- Write a concise description of the image for screen readers, or
- Mark the image as decorative if it's for aesthetic purposes only.
Click Save to insert the alt text.

PDF Viewer keyboard shortcuts

Command	Shortcut
Next page	N or J or →
Previous page	P or K or ←
Zoom in	Ctrl + +Command + +
Zoom out	Ctrl + −Command + −
Automatic Zoom	Ctrl + 0Command + 0
Rotate the document clockwise	R
Rotate counterclockwise	Shift + R
Switch to Presentation Mode	Ctrl + Alt + PCommand + Alt + P
Choose Text Selection Tool	S
Choose Hand Tool	H
Focus the Page Number input box	Ctrl + Alt + GCommand + Alt + G

Troubleshoot problems with the PDF viewer

With certain types of PDF files, the PDF Viewer may have problems displaying fonts, colors, or the whole document. If some PDF files don't render well or are blank, click the download button on the right side of the document header to open it with the default PDF viewer application on your computer.
If you can't open any PDF files with the built-in PDF viewer, a Firefox extension could be the cause. You can disable all of your extensions, to see if one of them was the problem. For details, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

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View and edit PDF files using Firefox’s built-in viewer

Table of Contents

Use Firefox’s built-in PDF Viewer

Fill out forms in PDF Viewer

Annotate PDF files