For testing APIs, I use a tool called Postman. Its free and available on the Chrome Webstore. Install and launch the app. To test an api call which requires authentication, turn on the Interceptor in Postman

Postman.Interceptor

This will prompt for a plug in to be installed in chrome.

Chrome.Interceptor

Once you to that, login to your application in chrome. The login credentials will be passed on to Postman and you can proceed with the API call testing.