Mozilla has released Firefox 19 this week and it has shipped with a built-in PDF viewer. This way users will not have to download a browser plug-in when opening PDFs in Firefox. The built-in PDF viewer in Firefox lets users change the size view, search documents for keywords, view page thumbnails, print PDFs, save PDFs to their computer, and bookmark it. Firefox 19 has been released around one month after Firefox 18. This update also features remote debugging, CSS improvements, and bug fixes. The PDF viewer in Firefox was built using HTML5.