Simply activate the add-on and perform the request. CORS or Cross Origin Resource Sharing is blocked in modern browsers by default (in JavaScript APIs). Installing this add-on will allow you to unblock this feature. Please note that, when the add-on is added to your browser, it is in-active by default (toolbar icon is grey C letter). If you want to activate the add-on, please press on the toolbar icon once. The icon will turn to orange C letter.
If you have a feature request, or found a bug to report, please fill the bug report form in the add-on's homepage.
