Charles is a Internet traffic monitor designed to provide you with detailed information about the data exchanged by your browsers and the websites that you are visiting. The program allows you to capture the requests and responses to analyze the traffic.
To capture the information, the program configures your computer to use itself as a dedicated proxy server which filters the data and provides you with the reports. It automatically changes the Internet options and installs the Charles Autoconfiguration extension which enables the proxy configuration in Firefox.
The interface of the application is easy to understand and displays the details about each visited website. Thus, you can view the loaded resources, HTTP headers, used protocol and response code for the current session.
The program automatically starts recording the traffic when you launch it for the first time but also offers the option to create new sessions which are displayed in separate tabs. It is a useful feature which allows you to compare the results across multiple time intervals and conditions.
In order to analyze a certain website you can specify the tracked URL and protocol for the traffic recorder. The same configuration window enables you to exclude certain addresses when they are not relevant for your analysis.
If you want to use the same parameters on multiple computers or migrate the application without losing the configuration, the app can export them to a file.
During our tests, Charles required insignificant resources and had no impact on the computer performance or Internet access speed. If necessary, the throttling feature can be used to simulate different connection conditions by changing the bandwidth and latency.
Charles is a useful tool for the developers who need to debug web applications and test their behavior under certain conditions.