Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
Find out which websites you can trust. WOT adds intuitive traffic light-style icons next to search results and URLs to help you make informed decisions about whether to visit a site or not.
Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Orkut, and many, many other sites. You can even customize Firefox and other programs themselves.
The Web Developer extension adds various web developer tools to the browser.
A customizable mouse gestures extension which enables to execute various commands and user scripts with six types of gestures.
Xmarks is the #1 bookmarking and open tab add-on. Keep your bookmarks, and open tabs backed up and synchronized across computers and browsers. Mobile phones with Premium access. Utilize LastPass to sync passwords!
Open Bookmarks/History/Homepage/URL/Search in new tabs, and more utilities for tabbed browsing, including Protect/Lock/Faviconize/Unload Tab, Reload Every, Select and manipulate multiple tabs simultaneously, Tab Stacking/Coloring, etc.
Set Default FullZoom Level,
Toolbar buttons for Page zoom and Text zoom.
Allows URI texts written in webpages to be loaded by double clicks.
Allows you to resize the window to specific dimensions.
NOTE: Users of Firefox 29 and above must install "The Addon Bar" extension to use this, as Firesizer uses the add-on bar that has been removed in Firefox 29.
Quickly test out your web pages in Internet Explorer, Chrome, Safari, or Opera. Open With opens the current page in your other browsers with just one click. Add Open With to your menus, toolbars and developer toolbox today!
Bring back your personal and powerful Firefox Button!