Global Proxy Preferences
You can proxy HTTP and HTTPS traffic from all OS X desktop applications by configuring your global proxy preferences.
Note the port number - Proxy.app listens on a designated port number (by default port
8080). To get the current port number simply open the Preferences from the application menu (key equivalent
Setup the system preferences - Navigate to System Preferences > Network > Advanced > Proxies. Select both Web Proxy (HTTP) and Secure Web Proxy (HTTPS) categories. Enter
localhost for the Web Proxy Server field and the port number of your proxy for the port field (port
8080 by default). Click on the OK button.
Apply the current network configuration - These settings will not be effective unless you click on the apply button.
Now you can observe and intercept all HTTP and HTTPS traffic generated from your OS X applications. Keep in mind that applications, which do not take advantage of OS X global preference will not be affected by this change.