Every once in a while you run across a free tool that makes tough problems trivial in a clean and simple way. I've used a handful of http debugging proxies, including those that aren't cheap, let alone free, and none of them hold a candle to Fiddler (www.fiddler2.com).
More than once I've been stuck with some cryptic browser problem that just wasn't a first-page google fix. And of course the problem is often different depending on the browser version, if it was over an https connection, etc. I recently had a problem where a dynamic pdf just would not open in IE when requested over ssl from IIS 7. The browser would just open a blank page so I had no error message to search on. I decided to fire up fiddler and compare the http with the https response. Sure enough, IIS was appending some no-cache headers to the response.
And that was just one issue. I've used Fiddler to:
- Inject CSS in order to test a style on a site I didn't host.
- Redirect traffic from mobile devices to my VS.net development server so I could avoid using my local IIS server.
- To see xml exchanged between Oracle and a SharePoint webservice.
Bottom line, if you anything with the web or the http protocol, download Fiddler today.