Two Ways to Disable Built in PDF Viewer in Mozilla Firefox

If you are tired using Firefox as default PDF reader program and want to disable built in PDF viewer in Firefox then this post will surely help you out. In this article two easy and effective methods are discussed which allows you to turn off Firefox PDF viewer Application. Once you disable built in add-on, you will automatically stop Firefox from opening PDF in browser.

First Method to Disable PDF Viewer Firefox!

This is the easiest and effective manner to disable built in PDF viewer in Mozilla Firefox. It includes editing Firefox's advanced configuration,by using this method you can easily stop Firefox from viewing PDF in browser.

  • Type about:config in the Mozilla Firefox address bar and press enter button.

  • A warning message will appears, confirm it to move on the next step

  • Search for pdfjs.disabledby using the search bar at the top.

  • You can see that the default value of the preference is set to false, it's meant the PDF reader is enabled.

  • Right click and press Toggle option or simply double click on the to disable it. Once you will disable add-on you can check the default value set to true. That's it.

Note: If still not working then make sure that the Chrome PDF viewer is enabled. Just paste "chrome://plugins/" on the search bar and press enter. If the plugin "Chrome PDF viewer" is disable then enable it now.

Second Method to Turn Off Firefox PDF Viewer!

This is another easy method to change required settings and stop using Firefox PDF viewer. So follow given bellow instructions to disable built in PDF viewer in Firefox.

  1. Tap on Alt key to show menu bar and move to the Option from Tool tab.

  2. Move to the Application tab and search PDF by using the search bar
  3. You will get three main actions for this feature. Choose always ask or save file to disable the Firefox PDF reader.


Above suggested both of methods to disable built in PDF viewer in Firefox are easy, effective & helpful. It works for me so I hope it will also work for you to stop Firefox from opening PDF in browser. You can also check how to enable firefox built in pdf reader in another post. Still, if you have any doubts or suggestions then put a comment below. Your feedbacks are also welcome.