Hi @Asallante,
Checkmk provides you with an REST API documentation plus an REST API interactive GUI.
Just open up your Checkmk and at the Sidebar you’ll find the Help button. There you can find the REST API documentation.
Keep in mind that the API is still WIP and is subject to change.
For more information on the API you can read this Checkmk article → Configuration via the Checkmk REST-API
Greetings Norm 