Firefox 15 tip: enable the built-in PDF viewer

Firefox 15 has been released. It comes with a built-in PDF viewer that is written in pure JavaScript (no plugins!) whose name is “pdf.js” [1]. To enable it,
  • go to about:config,
  • set pdfjs.disabled to false (double negation FTW!),
  • restart Firefox
Afterwards, all PDFs will be displayed inside Firefox and not be opened in external applications, any more.

Source: “What's New in Firefox 15” by Craig Buckler for SitePoint.


  1. PDF.js: display PDF files in your browser, without native code