What is Fiddler?
Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler includes a powerful event-based scripting subsystem, and can be extended using any .NET language.
Fiddler is freeware and can debug traffic from virtually any application, including Internet Explorer, Mozilla Firefox, Opera, and thousands more.
Came across this tool today, and I’m quite impressed.
Watch the videos! I’ve been looking for a tool like this for long.
A warning: You have to stretch you security if you want to monitor Outlook traffic, as Outlook requires a valid certificate. Read more here.