Fiddler

About Fiddler

You may use it to check incoming and outgoing data, as well as monitor and alter requests and replies before they reach the browser. Fiddler also comes with a robust event-based scripting system that you may modify with any.NET Framework language. Making an offline duplicate of the test site with Fiddler and the HTTP replay features might help you debug client-side issues with web applications. You may use these tools to produce offline pictures of the browsing experience.