View PDF files in Firefox or choose another viewer

Firefox Firefox Last updated: 03/14/2024 50% of users voted this helpful
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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.)

Fx91PDFviewerFirefox PDF viewer - updated V122

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 Fx98PDFviewer-DownloadButtonFx106 PDF dl button 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.

Fx105 PDF FormsFirefox PDF fill out forms - updated v122

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.
    Fx105 PDF SidebarFx106 PDF Sidebar
  • 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.
    Fx105 PDF PagerFx106 PDF Pager
  • Change the size of the document: Use the + and buttons to zoom in and out or choose a zoom setting from the dropdown menu.
    Fx105 PDF ZoomFx106 PDF Zoom
  • Fullscreen or Presentation mode: Click the Presentation Mode button to allow the PDF file to take over your entire screen. Press Esc to exit fullscreen mode.
    Fx105 PDF Presentation
  • Print: Click the Printer button to open the print setup dialog.
    Fx105 PDF Print
  • Download: Click the Download button to save the PDF file to your computer.
    Fx105 PDF Download
  • Copy current view: Right-clickHold down the control key while you click the current view button to open the current view in another tab or window.
    Fx105 PDF Current view
  • Print: Click the Printer button to open the print setup dialog.
    Fx106 PDF Print
  • Download: Click the Download button to save the PDF file to your computer.
    Fx106 PDF Download

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 Annotate PDF 1 to choose a color and text size before selecting where on the document you wish to add text.
  • Click Annotate PDF 2 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

  1. To highlight text or an area in a PDF document, first select the desired text or area. Then, click on Firefox PDF highlighting option.
    Firefox PDF select text to highlight
  2. Choose your preferred highlight color and adjust the thickness of the highlight.
    Firefox PDF highlighting settings

Show/hide all highlights

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

Edit or delete a highlight

  1. Click on the area you previously highlighted.
    Edit or delete Firefox PDF highlight
  2. To change the color of your highlight, click on Color selection dropdown for PDF highlight and select a new color.
  3. To remove the highlight, click Trash can icon.

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:

  1. On the top right of the screen, click Add image to PDF 2.
  2. Click + Add image. This will prompt the file selection window.
  3. Browse and select the desired image file to add it to the PDF.

Repositioning and resizing the image:

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

Adding Alt Text for accessibility:

  1. After adding the image, click + Alt text.
  2. 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.
  3. Click Save to insert the alt text.
    Add image to PDF

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

Use a different PDF viewer for downloaded PDF files

When Firefox is set as the default PDF viewer, and you download a PDF file in Firefox and save it to your computer, you can use a different application to view those PDF files by following these steps:

  1. Open the Downloads panel by clicking the Fx91DownloadsButton download icon next to the address bar. (Alternatively, open the Downloads Library window.)
  2. Right-clickHold down the control key while you click the download entry for the PDF file you want to open.
    Fx99DownloadsPanel-PDFcontextmenu-WinEdit PDF 2
  3. Click the context menu item for the system default PDF viewer (for example, click Open in Adobe Acrobat Reader DC) (for example, click Open in Preview) to open the PDF file in that application.
Note: If you want to view a downloaded PDF file in another application, open the Downloads panel or Library window as explained above, but click the file folder icon Fx91DownloadsPanel-OpenFolderIcon for the PDF file entry. This will open the folder containing the downloaded the magnifying glass icon MagnifyingGlass for the PDF file entry. This will open the folder containing the downloaded file in Finder. You can then right-clickcontrol-click the file, select Open with and choose the PDF viewer application you wish to use.

Choose another PDF viewer to use by default or set Firefox to always ask

Note: When you choose another PDF viewer to use by default in Firefox, or, if you set Firefox to always ask you what to do with PDF files, any PDF files you open will also be saved to your Downloads folder (see Where to find and manage downloaded files in Firefox).

Disable the built-in PDF viewer and use another viewer

Note: If Firefox is not your current default PDF viewer, you will be prompted to set it as the default when opening a PDF file in Firefox.

Set FF as default PDF viewer prompt

You can also set a different third-party PDF viewer to handle PDF files, instead of Firefox’s built-in PDF viewer. To switch from using the built-in PDF viewer to another viewer:

  1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button Fx89menuButton and select Settings.
  2. In the General panel, go down to the Applications section.
  3. Find Portable Document Format (PDF) in the list and click the entry to select it.
  4. Click the arrow under the Action column for the above entry and select the PDF viewer you wish to use from the drop-down menu.
    Edit PDF 3Fx78Applications-PDFFx78Applications-PDF-Win
Note: When Open in Firefox is the selected action, the built-in PDF viewer is used.

Set Firefox to ask you what to do with PDF files

If you want Firefox to always ask you what to do with PDF files, follow the above steps to change the action for the Portable Document Format (PDF) entry, except select Always ask from the drop-down menu. The next time you click a link to download a PDF file, Firefox will show you a prompt asking what to do with the file. You can then choose to open it with Firefox's built-in PDF viewer, open it with a different PDF application, or you can choose to save the file.


For more information, see Manage file types and download actions in Firefox.

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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