Mozilla Firfox 21.0
Features include tabbed browsing, spell checking, incremental find, live bookmarking, smart bookmarks, a download manager, private browsing, location-aware browsing (also known as "geolocation") based on a Google service[29] and an integrated search system that uses Google by default in most localizations. Functions can be added through extensions, created by third-party developers,[30] of which there is a wide selection, a feature that has attracted many of Firefox's users.
Additionally, Firefox provides an environment for web developers in which they can use built-in tools, such as the Error Console or the DOM Inspector, or extensions, such as Firebug.