A free tool to debug and fiddle with Internet traffic

Successfully debugging Internet traffic problems requires being able to see what's really happening in the HTTP and HTTPS traffic to and from the user agents.

While developer tools in Firefox and Chrome can help, another free tool you can use to debug Internet traffic is Fiddler. Fiddler logs all HTTP and HTTPS traffic, letting you inspect it, set breakpoints, and experiment on the data going through. You can also write scripts for Fiddler using .NET.

Fiddler can be used for debugging problems experienced with browsers on computers or other devices, as well custom applications connecting to the Internet.