Last updated:
41% of users voted this helpful
Firefox includes a built-in PDF viewer that lets you view PDF files directly in your browser. This article will show you how to use the built-in PDF viewer and how to resolve common issues.
- To learn how to switch to another PDF viewer, see Choose your preferred PDF viewer in Firefox.
Table of Contents
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 needing an external application (exceptions include PDF files with an incorrectly set MIME type). The built-in viewer is automatically used when PDF files are set to in your Firefox settings for different types of files, which is the default setting. When you click a link to a PDF file or open it from the Firefox Downloads panel, it will open with the built-in PDF viewer.
The PDF file will open directly in Firefox without being saved. To save the PDF to your computer, click the download button in the PDF viewer’s toolbar.
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.
PDF Viewer toolbar functions
- 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
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 . 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 .
- 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 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.
