I would like to know if there are any applications like fiddler but for mac OS X, as I need to debug some requests from web applications in Mac OS X. I used to do it with fiddler on Windows and would love to have this tool available on Mac as well.
The free Tamper Data Firefox extension is pretty good. Allows you to view, filter and modify all requests.
HTTPScoop is awesome for inspecting the web traffic on your Mac. It's been incredibly helpful for me. I didn't think twice about the $15 price tag. There is a 14 day trial.
WebScarab is a framework for analysing applications that communicate using the HTTP and HTTPS protocols. It is written in Java, and is thus portable to many platforms. WebScarab has several modes of operation, implemented by a number of plugins. In its most common usage, WebScarab operates as an intercepting proxy, allowing the operator to review and modify requests created by the browser before they are sent to the server, and to review and modify responses returned from the server before they are received by the browser. WebScarab is able to intercept both HTTP and HTTPS communication. The operator can also review the conversations (requests and responses) that have passed through WebScarab.
http://www.owasp.org/index.php/Category:OWASP_WebScarab_Project
Charles is written in Java and runs on Macs. It's not free though.
You can point your Mac at your Windows+Fiddler machine: http://www.fiddler2.com/fiddler/help/hookup.asp#Q-NonWindows
And as of 2013, there's an Alpha download of Fiddler for the Mono Framework, which runs on Mac and Linux. Also, the very latest version of Fiddler can import .PCAP files captured from WireShark or other tools run on the Mac.
In case you are using Eclipse you might try http4e
If you don't get any direct answer to this you could always run Fiddler on a windows machine and configure your browser on the Mac to use the windows machine as a proxy server. Not very satisfactory and requires a second machine (although it could be virtual).
Cocoa Packet Analyzer is similar to WireShark but with a much better interface. http://www.tastycocoabytes.com/cpa/
I think the possibilities are less, but FireBug (addon of FireFox) has some network analysis tools, too.
Charles is an excellent Web Debugging Proxy for Windows, Mac OS and Linux. The full version is 50$ but it's well worth it.
I know this is an old question, but I wanted to add ServiceCapture to the list, for those who may come across this.
I've been using ServiceCapture for about 4 years and love it. It's not free, but it is a great tool and not very expensive. If you debug a lot of Flash or AJAX apps it is invaluable.
Source: Stackoverflow.com