If you work in or around web applications or web servers and you do not know what fiddler is, than I feel really sorry for you. This tool is one of the first utilities I launch when I see something that makes me suspect issues with cookies, server redirects, or any other odd behaviors where I hear "It worked fine on my machine". The developers I work with are more then sick of hearing, "did you launch fiddler?" They know to have it up and running before asking me, "do you have a sec? " With fiddler it turns those scratch your head moments into a decision of whether it is the browser or the server acting funny.
What is Fiddler?
It is an http debugger which inserts itself as an http proxy which exposes all of the web browser requests and server responses into a simple debug window. It allows you to drill down into each request to verify the actual data being sent back and forth. Oh yeah.. I have seen some articles which explain how to setup .Net code to run through the fiddler proxy. How is that for versatile? It is extreamly powerful and a must have tool, if you are stuck programing against a custom XMLRPC interface.
Where Is it?
Get it here: http://fiddlertool.com/fiddler/
Can it solve world hunger?
No it cannot do that. It also cannot let you see the data in an SSL/https session. There are some extensions that let you see some ssl headers, but it is a limitation of the tool so you need to know that going into using this tool. As a result I make sure that our applications do not force us into a situation where I cannot perform the same task on a site in http as we can do in https. That is a little bit off track right now...I will get to that in a future post.
Good luck debugging and get fiddler!
Eric Hexter