Fiddler is a free Web Debugging Proxy that integrates with Internet Explorer, Mozilla Firefox, Opera and other Web browsers. It registers all incoming and outgoing traffic from a computer to the Internet and is even capable of working with instant messaging programs.
This program is mostly designed for the network administrator who needs to monitor traffic by user sessions whether it’s locally or remotely. It collects Web and usage statistics, identifies errors and has other different analysis tools that will output a complete report of the traffic.
It is capable of monitoring many other applications, especially those that use the WinInet protocol like Office and Messenger. The main GUI shows a session and when double clicking, the traffic inspector becomes available and displays request and response information about all http traffic. Users can create notes and breakpoints on the traffic log for later inspection.
This program is not for inexperienced users since its tab-like interface, though very simple, is not easily understood or self explanatory. Fiddler’s web site has complete documentation on the program that includes Power Point presentations and instructional videos if you want to learn how to use it (http://www.fiddler2.com/Fiddler/help/).
Version 2.2 has several additions. It has support for BZip2 compression. New options that have been added: ‘monitor all connections’, ‘commenting on sessions’, and ‘decode compressed content to find sessions. Fiddler now also hooks all connections by default, allows drag/drop files to AutoResponder to create new rules. Plus other new features include 64bit OS support and Windows 7 compatibility.