In your omnidesk application a key can be created to which certain permissions will be granted. You could for instance assign customer creation and deletion to a key. Most permissions are devided in two categories: READ permissions and CUD (create update delete) permissions for a given endpoint. Once you have created a key and given it permissions you will be able to authenticate with it by sending ?apiKey=[[ your key ]] in the API url.

An example would be: Since this is a GET request for the customer endpoint it will list all customers, limited by paging.