In order for any browser (or any application) to use Charles it must be configured to use Charles as its proxy server. Most browsers will have a way to configure this manually, but configuring manually is annoying because you have to configure and reconfigure everytime you start and stop Charles.

Fortunately Charles can autoconfigure the proxy settings in many cases including:

• Windows / Internet Explorer proxy settings
• Mozilla Firefox proxy settings (all platforms)
• Mac OS X / Safari proxy settings

For Windows and Mac OS X the proxy settings are global for the whole system and are used by most applications. So all networking applications on either of those platforms should use Charles without the need for any further configuration.

The Mozilla Firefox proxy settings are managed using a Firefox extension that is available for download alongside Charles.