Firebug is licensed under the BSD license and was initially written in January 2006 by Joe Hewitt, one of the original Firefox creators. The Firebug Working Group oversees the open source development and extension of Firebug. It has two major implementations: an extension for Mozilla Firefox and a bookmarked implementation called Firebug Lite which can be used with Google Chrome.
In addition to debugging web pages, Firebug is a useful tool for web security testing and web page performance analysis.
Firebug makes changes immediately and gives constant feedback to the user. All editors in Firebug support auto complete.
HTML and CSS
The HTML and CSS tools allow for the inspection and editing of HTML and CSS elements on a web page. Later versions of Firebug allow users to see live changes to the CSS. Visualization of CSS elements is shown while inspecting HTML elements. The Firebug layout tab is used to display and manipulate CSS property values. Furthermore, users can click on any visible HTML elements on a web page to access its CSS property values.
Many extensions have been made to enhance the Firebug experience. Since Firebug is open source, users can contribute their own extensions to the Firebug community.