Turn on Built-in PDF Reader in The Latest Version of Firefox

If you are a Firefox user, you can now open PDF files right from your browser without installing any Adobe or Foxit plugin. Mozilla’s recently released version Firefox 15 has a PDF reader built-in just like Google Chrome. This interesting feature has to be turned on; this is not enabled by default. The reasons why built-in PDF reader is important are- first of all it speeds up the execution of files online, secondly security where Adobe fails. With this new feature, we can now have a more stable and secure online viewing of PDFs.
NOTE:  Before using this built in PDF reader, you need to disable Adobe or Foxit plugin if you already have those installed. More advanced features are not yet available in built-in plugin. So if you are a PRO you might still need Adobe or Foxit plugin.

To enable this feature, in the address bar, type about:config the line below and then press Enter.

Next, click the button “I’ll be careful, I promise!” to proceed.

Search for browser.preferences.inContent.

When you find it, right click on it and from the context menu, select Toggle or double-click the entry.

Next, you need to enable built-in PDF reader feature, search for pdfjs.disabled.

Again, right click on it and from the context menu, select Toggle or you can double-click the entry.


Now, you can view PDF files using the built-in reader. If you have PDF files saved in your computer, you can view them in Firefox by dragging and dropping them into Firefox or using the Open with menu.