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Alternative HTTP debugging proxies, for debugging

I've previously mentioned the value of using HTTP debugging proxies, which help you observe the communications out of your browser and back, which can be especially helpful debugging problems with Ajax and Flex/Flash apps as well as general-purpose web apps. Though I've pointed out a couple of my favorites (Fiddler and Firebug) before, here is a larger list. "To each his own", as they say.

Most are free, some are browser-specific, and I've tried to break the list up that way. These tools are also referred to as MITM, or Man In The Middle, proxies or http sniffers.

[Update: Since writing this in 2006, most modern browsers now provide this sort of client proxy/debugging functionality built-in. I wrote about them in a 2012 blog entry. Also, I long ago moved this list (and more such tools) above to a new location with far more updated info: a category in my CF411.com list of tools and resources for CFers.]

And there are still other ways to do the kind of communication analysis, including tcp trace tools and even a Sniffer and a tcpmon tool, both built into CFMX and useful for watching the http traffic going into CF. There's also the NetConnection Debugger for Flash and Flex. Still, I'm limiting this discussion just to HTTP debugging proxies. If folks know of still others, feel free to add them in the comments.

Free, General-purpose HTTP Debugging Proxies

Free, IE-only Proxies

Free, Firefox-only Proxies

Commercial Proxies

I'd like to point out as well that this list appears, along with other similar lists of tools related to CF, on an older site I still maintain: http://www.systemanage.com/cff/considering_products.cfm

It's a bit of a sledgehammer, but I will generally just fire up Ethereal:


But then, I use it for other things as well, and it's nice having one tool that solves all of my network-traffic-sniffing needs. It also has a pretty comprehensive logging and filtering interface, so that I can show just the stuff that I want, then replay it later.
# Posted By Rick O | 11/28/06 2:53 PM
Hi Charlie,

Great list of Debugging Proxies. I can add this one:

Charles from Karl von Randow

Charles is a Shareware HTTP proxy / HTTP monitor / Reverse Proxy that enables a developer to view all of the HTTP traffic between their machine and the Internet. This includes requests, responses and the HTTP headers (which contain the cookies and caching information), and can process AMF (Flash Remoting) packets too!


# Posted By Darren Pywell | 11/28/06 2:59 PM
Thanks, Rick. Yes, Ethereal was one of that class of TCP tracing tools/sniffers that I was alluding to but wasn't planning to list. Still, no problems with your listing it. Folks can indeed consider it. As you say, it can be a bit much.

And thanks, Darren, for the mention of Charles. I do now recall it, but couldn't find it as a I dug around for some of the ones I'd heard of. Thanks.
# Posted By Charlie Arehart | 11/28/06 3:08 PM
FriendlyGhost (www.orison.biz/products/)

its specialy built for Flash/Ajax debuging.

// chall3ng3r //
# Posted By chall3ng3r | 11/28/06 5:02 PM
One of the first proxies I used was achilles:

Though Charles is the best one out there at the moment. Though it's a little bit expensive.

# Posted By Daniel Tome | 11/28/06 5:32 PM
Alongside a subscription email for this thread, an announcement of Komodo Beta 2 just hit my Inbox with this nugget:

"HTTP Inspector: An interface for examining HTTP requests and responses as they happen. It runs a local proxy which intercepts HTTP traffic and records each transaction, which can then be viewed. The Inspector can break on a request or response, which can then be edited and submitted or re-submitted in its modified form."

I haven't used Komodo much at my current job (mostly CF via HomeSite and CFEclipse), but it was invaluable at my last job (Perl and PHP).


# Posted By Rick O | 11/28/06 6:03 PM
If you do CF work, then there's also Apache Axis TCPMonitor available as simple executable, should be at \Jrun4\bin\sniffer.exe under Windows. You can even simulate slow connections with it (not as easy as in ServiceCapture though).

More on TCPMonitor usage:
# Posted By Erki Esken | 11/28/06 7:21 PM
Thanks for the extra ideas, gents.
# Posted By Charlie Arehart | 11/28/06 10:13 PM
I'd also like to recommend the Charles HTTP Proxy. It's pure Java and runs well on Mac OS X. The AMF support is fantastic. I purchased the product after evaluating many others. The developer has been very responsive to problems and suggestions. Updates to the application are released frequently with new features, bug fixes, and improvements.

I swear, I'm not getting a nickel for this testimony! :)
# Posted By Joseph Lamoree | 11/29/06 11:23 AM
My vote goes to charles as well..

It's actually the first piece of software i payed for in years, except flashcom and OS/X, which came with the laptop..

Multi-platform and like mentioned earlier.. great response times
# Posted By Evert | 12/4/06 8:36 PM
..great reponse times in terms of support i meant to say
# Posted By Evert | 12/4/06 8:36 PM
Good post about proxies. I'm looking for something like it. Thank you, Charlie!
# Posted By Andrew S. | 9/25/07 10:54 AM
"Charles" is indeed one of the best in this kind. Great interface, great responses time. A must-have.
# Posted By realk | 11/23/07 12:50 PM
Another vote for Charles - I was evaluating it and had a problem with the external proxy authentication. Karl was very responsive and I had a new version a few weeks after explaining my problem. It rules!
# Posted By Ian McGowan | 1/11/08 12:11 PM
Another good HTTP analyzer:
# Posted By pka | 2/24/08 9:58 AM

You can use the HTTP Debugger

which works not only with IE or FireFox but also with custom developed programs and system services.

# Posted By HTTP Debugger | 3/11/08 12:52 AM
Thanks, KP. I should add (for you and all readers here) that I have indeed previously added that (and other new tools) to the original list from which this blog entry was created, which can be found at:


I don't think it will make sense to keep both lists up to date, so I'd recommend people please go visit there to see if I have indeed already added a tool, before suggesting it here.

Of course, that also means that those looking for more of these tools should look at the link after reading the above.
# Posted By Charlie Arehart | 3/11/08 5:10 AM
Hi Charly,
I want to add Membrane Monitor, a HTTP proxy sniffer with a CLI and a GUI based on the Eclipse RCP platform. For XML messages it has a formatter.

# Posted By Thomas Bayer | 12/10/09 3:16 PM
Done. Thanks for the heads up, Thomas.
# Posted By Charlie Arehart | 12/10/09 4:39 PM
Firebug is also my favorite and I love how they keep adding possibilities and features. Thanks for the great list by the way!

# Posted By Emily Niederhauser | 4/8/11 1:17 AM
It's actually the first piece of software i payed for in years, except flashcom and OS/X, which came with the laptop..

Multi-platform and like mentioned earlier
# Posted By anon | 4/10/11 10:21 PM
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