For testing our API methods without writing any code you can do the following:
Create an API User from your BSS. Navigate to BSS > Setup > Administration > System Options > API Credentials and create an application user
Navigate to API documentation and select “Authorize”
In the pop-up form enter the credentials of the application user you created and the client_Id and client_secret than can be found in the API credentials page.
Select them the “try it out” button in any method you want to test