View PDF files in Firefox or choose another viewer

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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.

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 on 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 Using Firefox's built-in PDF viewer, below.)

Fx91PDFviewerFx106 PDF viewer

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.

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 on the download entry for the PDF file you want to open.
  3. Click on the context menu item for the system default PDF viewer (for example, click on Open in Adobe Acrobat Reader DC) (for example, click on 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 on the file folder icon Fx91DownloadsPanel-OpenFolderIcon for the PDF file entry. This will open the folder containing the downloaded on 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 on 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

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 select Preferences.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 on the entry to select it.
  4. Click on the arrow under the Action column for the above entry and select the PDF viewer you wish to use from the drop-down menu.
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 on 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.

Using Firefox's built-in PDF viewer

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 FormsFx106 PDF forms

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

Click the Text button to choose a color and text size before selecting where on the document you wish to add text. Click the Draw icon 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.

Fx 106 PDF annotate

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.

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