How to enable built-in PDF Viewer in Firefox 15

Mozilla sometime earlier released the newest version of its open-source, cross-platform web browser – Firefox 15. The browser runs with reduced memory usage for add-ons, has a new JavaScript debugger and more. It is compatible with both, 32-bit and 64-bit versions of Windows OS.

Also, Firefox 15 features a built-in PDF Viewer but it is not enabled by default. So, this becomes our topic of discussion. In this post, I will guide you through the process of enabling the built-in PDF Viewer in Firefox 15.

Why has the feature not been enabled by default? Because, the PDF Viewer is still in the Beta state and therefore you have to manually enable it.

Enable built-in PDF Viewer in Firefox

Open Firefox browser and in the address bar type the following – ‘about: config’ and hit ‘Enter’.

Firefox about config 600x270 How to enable built in PDF Viewer in Firefox 15

Instantly, a warning will be displayed on your computer screen with the following message – This might void your warranty. Changing these advanced settings can be harmful to stability, security and performance of the application. Just ignore the message and hit ‘I’ll be careful, I promise!’ button.

Once you do it, a big list will be visible to you.

Firefox list 600x279 How to enable built in PDF Viewer in Firefox 15

In the search box, type ‘Browser.preferences.inContent’.Firefox browser preferences How to enable built in PDF Viewer in Firefox 15

After you find the same address in the list, right-click on it and choose the Toggle option. This should change its value from ‘False’ to ‘True’.

Firefox Toggle 600x369 How to enable built in PDF Viewer in Firefox 15

Do the same for other address – pdfjs.disabled! Type pdfjs.disabled in the search box.

Firefox Toggle 31 600x375 How to enable built in PDF Viewer in Firefox 15

When found, right-click on the option and choose ‘Toggle’ again. This will change the value from ‘False’ to ‘True’.

Firefox toggle 2 How to enable built in PDF Viewer in Firefox 15

That’s it!

The Firefox built-in PDF Viewer has now been enabled. Simply visit a linked PDF document of any website and it should open in the browser. See the screen-shot below.

Firefox PDF File 600x299 How to enable built in PDF Viewer in Firefox 15

Firefox’s built-in PDF viewer is just a basic PDF files viewer for Firefox browser. If you would like to access more advanced PDF features you’ll need the Adobe or Foxit plugin.

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The author Hemant Saxena is a post-graduate in bio-technology and has an immense interest in following Windows, Office and other technology developments. Quiet by nature, he is an avid Lacrosse player. Creating a System Restore Point first before installing a new software, and being careful about any third-party offers while installing freeware is recommended.
  • howiem

    I was using Sumatra pdf in FF15.0.1 and running the browser in a sandbox (sandboxie). I made the changes per this tip, disabled the Sumatra pdf plugin and restarted Firefox, searched for a PDF file, and tried to open it, but instead of seeing the file open using the Firefox PDF reader, I was offered the save or open with option.
    What I would like to know is whether or not the FF PDF reader has the capability to search a pdf file? I cannot tell from the image above

  • Beppe

    I clearly read “Find” as a cue text to a text field in the pdf pane…

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