In Firefox 15, the built-in PDF viewer is an experimental feature, so it is disabled by default (read below to know how to enable it). Even though, it is an experimental feature, from my experience I would say it is working (opening and reading PDF files) flawlessly. How to enable PDF viewer in Firefox Open your Firefox browser and type about:config in the address bar and hit enter key to launch Firefox’s configuration page. Don’t forget to accept the warning by clicking “I’ll be careful I Promise” button.
Now, start typing pdfjs.disabled in the search box to find the pdfjs.disabled option. By default, its value is “true”. Double click on it to make its value “false”. Then, close about:config tab and try the new feature by opening a pdf document. For that, just right click on PDF document and select open with Firefox. Final thought: By comparing both Chrome’s and Firefox’s PDF reader functionality, both are basic PDF viewers. In Chrome, there is no option to select individual pages, but Firefox has this, which is a plus point for Firefox.
