- NoScript - Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.
- HTTPS Everywhere - HTTPS Everywhere is a Firefox and
Chrome extension that encrypts your communications with many major
websites, making your browsing more secure.
- Better Privacy - Remove or manage a new and uncommon kind of cookies such as LSOs and Flash cookies
- GUI:Config - This extension provides a nifty GUI frontend to about:config for making advanced configuration tweaks for your Firefox browser
- Gmelius - Gmelius is a cross-browser extension that proposes a better and cleaner Gmail inbox.
- Hola Unblocker - Hola Unblocker is a browser extension that removes region locks and allows you to watch BBC iPlayer, Netflix, Hula, Pandora, and more regardless of where you live. It doesn't require any set up and works right out of the box.
- Shumway - Shumway is Mozilla's HTML5 Flash Player that is intended to be a Flash plugin replacement. See also: TechCrunch's report / Shumway's Github Repository
- Lifehacker Pack for Firefox 2013: Our List of the Best Extensions (Lifehacker)
- The Best About:Config Tweaks That Make Firefox Better (Lifehacker)
- MozillaZine - About:Config Entries (Mozilla)
- The Always Up-to-date Power User's Guide to Firefox (Lifehacker)