Firebug is an extension for Mozilla Firefox written in JavaScript, XUL, CSS. The tool is useful for software developers and testers.

It is mostly applied for debugging web pages, security testing and performance testing of web software products.

Firebug shows HTML code of any web page, helps to detect location of the web page elements and inspect them. It enables its users to edit HTML, CSS, JavaScript code directly in the browser.

The changes come into operation immediately. It monitors the process of a web page loading, shows HTTP-headers and AJAX-requests.

Firebug functionality can be extended by a number of utilities, they include Firecookie, FirePHP, FireRainbow, YSlow.

Firebug is free and open-source, it is developed by Joe Hewitt.

Tool Usage in Our Projects

Web Application Testing


Functional Testing


User Interface Testing


Related software testing tools