Every request is validated and authenticated by the API-key header. You can view your API-Key when you are logged into the web-app in https://live.hellotracks.com, open API & Integrations page under More in the main menu. Make sure to enable APIs in the API section. 
curl -X POST https://api.hellotracks.com/api/$endpointname \\
    --header 'API-Key: ABCDEF.ABCDEFGHIJKLMNOPQRSTUVWXYZ123456' -d \\
'
    {
        "data":{
          ...
        }
    }
'
Parameters for endpoint are defined in the required data field. All endpoints use the POST method.