Web Developer is an extension that adds a toolbar to web browsers such as Firefox, Flock, Mozilla or Seamonkey with options often used by developers. Among the features offered by the additional toolbar you will find such as enabling / disabling Java, JavaScript, cookies, displaying images, tables, etc. The application also allows you to obtain detailed information about the page viewed, determine the resolution for it, edit the sources in real time on your computer's hard drive or carry out an error analysis on the website using external pages verifying the correctness of the code.

The extension cooperates with the above mentioned browsers also on Linux and Mac OS X systems.