When it comes to inspecting and tampering with the HTTP(S) traffic from our computer and the Internet, the most popular tool you can find is Fiddler. This is a freeware tool that allows inspecting all HTTP and HTTPS traffic and tampering it, setting breakpoints, making it an ideal candidate for debugging applications.
It also offers an event-based subscription system offering the capability to easily extend it. Install Fiddler from
http://www.fiddler2.com/Fiddler2/
. You can find a quick introduction to Fiddler on MSDN, and in the following resources:
Fiddler tutorial
http://www.developer.com/lang/jscript/article.php/3631066
Fiddler2 demonstration videos
http://www.fiddler2.com/fiddler/help/video/default.asp
Fiddler2 extensions development
http://www.fiddlertool.com/fiddler2/extensions.asp
Fiddler2 user interface
http://www.fiddler2.com/Fiddler/help/ui.asp