The firefox-mac-pdf add-on lets you view PDF files right within Firefox.

I just switched from Safari to Firefox as my default Web browser, but the one thing that I miss is the ability to view PDFs right within the browser itself. Can I make this happen within Firefox?

Unlike Safari, Firefox makes you download PDFs to your hard drive in order to open them. This can be a nuisance after you’ve become accustomed to Safari’s convenient method of displaying PDFs directly in your browser window.

But, fortunately, Firefox has an active developer community that creates handy add-ons you can use to personalize your browsing experience. Some can be found on Mozilla’s list of Firefox Add-ons (addons.mozilla.org/en-US/firefox), and many more are strewn about the Internet, found by searching.

One add-on, called firefox-mac-pdf (free, code.google.com/p/firefox-mac-pdf/), makes Firefox act more like Safari. It takes advantage of the native PDF tools built into Mac OS X to display your PDFs in Firefox’s browser window, just like you’re used to.