This is not particular insightful tip, but often when I use Fiddler for debugging non-IE requests with customers or during training sessions I hear they didn’t know that they can use Fiddler with any browser, not just IE.

I’m working with a customer today regarding a funky Session and Cookie problem in their application and we’ve been using Fiddler to track through the HTTP sessions. Fiddler is easy to use and provides a nice easy interface to look at the result content. I especially like the Raw view that was added in the latest version to let you see the raw HTTP client request and raw response that includes all of the headers…

Anyway as we were working through this problem we found out that the issue came primarily through non-IE browsers. Fiddler is primarily touted as an Internet Explorer add-in, but several of the developers I worked with today didn’t realize that you can actually use it with any browser. Fiddler works as a proxy server and it just happens that it automatically configures Internet Explorer’s Proxy settings so that as soon as you start Fiddler, IE automatically uses the proxy. Other browser do not…

But... Fiddler is a standalone application and because it is essentially a Proxy server that intercepts and picks up your request data, you can use it with any browser including FireFox.

All you need to do is:

  • Open FireFox options
  • Go to General | Connection Settings
  • Use the Manual proxy configuration option
  • Set t 127.0.0.1  Port 8888

If you forget the port number, you can look up the port Fiddler is listening on in the Fiddler options.

Make sure you remember to remove the proxy settings when you’re done in FireFox…