With Firefox 16, you can enable the built-in PDF viewer which will automatically open the PDF files in the browser itself. This option is disabled by default. So you need to enable it to make this feature work properly. No Add-on or Plugins required.
Enable the built-in Firefox PDF viewer
- In the Firefox address bar, type about:config and hit enter.
- You’ll prompted with a message that says ”This might void your warranty!” …… Click on the I’ll be careful, I promise! button which is below the message.
- In the Search: field, type pdfjs.disabled
4. You should get only one entry for this particular search in the Preferences section below it. Double click this entry to change the Value to false.
5. This enables the built-in PDF viewer facility in Firefox. Now restart Firefox.
Please note: If you have the Adobe Acrobat add-on (Plugin) in your list of add-ons, you need to disable it. Going to the Add-ons Manager in Firefox, MenuBar>Tools>Add-ons or by clicking the Firefox button at the top left hand corner of the browser and clicking Add-ons on the right side of the pop-up menu that opens up.
Now when you open a link to a PDF file in Firefox, the PDF file will open in the browser window or tab itself.