Charles is a web debugging proxy server tool that lets you view all traffic over an HTTP or HTTPS connection. It works on all the popular platforms like Windows, Linux and macOS. Using this proxy you can both monitor and debug the way your computer interacts with various web servers as you try to open a website in your web browser.
In Windows, I found out that Charles Proxy does not work right out of the box and we have to take some extra steps to make it work. This is because of the problem in finding the installed JRE on your Windows PC. You can follow these steps to properly install and configure Charles Proxy in Windows and use it with Firefox browser:
- Download Charles Proxy for Windows from https://www.charlesproxy.com/ and install it.
- Download JDK 13 from https://www.oracle.com/technetwork/java/javase/downloads/jdk13-downloads-5672538.html and install it in Windows.
- Open the folder C:\Program Files\Charles, find Charles.ini file and open it in Notepad.
- Replace the line that begins with vm.location with vm.location=”C:\Program Files\Java\jdk-13\bin\server\jvm.dll”. Save and close Charles.ini after this.
- Launch C:\Program Files\Charles\Charles.exe and when Charles Proxy windows shows up, ensure that Windows Proxy option is checked under the Proxy menu.
- Now launch Firefox browser, open Options and then Network Settings. You have to select System Proxy from the proxy settings for Firefox and save the settings.
- Now Charles Proxy is configured to work with Firefox browser. Any website you open in Firefox will be routed through Charles Proxy server and you will see all the details in the Charles interface.
Charles is a really very powerful proxy server and it even works with the HTTPS secure connections. Some of the websites using SSL secure connection might fail to work unless you install Charles SSL certificate in the browser. You can install SSL root certificate in Windows by choosing SSL Proxying → Install Charles root certificate from the Help menu of Charles Proxy window.