This post is for all the web developers among us. Charles: Web Debugging Proxy is an excellent application for Windows, Mac OS X, and Linux that monitors and displays http traffic. I was motivated to seek out a program like Charles because I was debugging an AJAX application, and needed to examine what was going on between the client and server. Charles was a perfect fit — it will show you everything that is being exchanged back and forth by your browser and the sites with which you communicate. As the author says, Charles is also useful for Flash developers who would like to see what is going on underneath their animations. Charles can even throttle your bandwidth so that you can experience your sites as a modem user would.
All the non-web developers out there might be wondering just what I am talking about. Well, have you ever wondered what happens when you type in a web site’s address, click a link, or interact with a web application? Well, a lot of information is exchanged back and forth between your computer and the sites you are visiting. Charles monitors this exchange of information, and shows you everything that passes through your network connection. Give Charles a try — you may not understand everything you see, but you might also be very intrigued.
In order to see Firefox’s activity, Charles requires you to install a Firefox extension. The extension is available on Charles’ download page.
Charles is shareware; after 30 days, you must pay a $50 licensing fee. I chose to write about Charles despite the hefty price tag because I was extremely impressed by it’s presentation and ease of use. Similar software without the price tag includes Fiddler and ngrep.
