The World Magnetic Model API calculates the intensity and direction of the Earth's magnetic field on a specific date-time, geodetic altitude, latitude, and longitude. It is relied upon throughout the world for navigation, mineral exploration, atmospheric and space science, and is installed on billions of devices. A comprehensive description of the World Magnetic Model, including its limitations, can be found in the documentation. We provide a RESTful API to the World Magnetic Model for free access to the out-of-cycle WMM (WMM2015v2) valid for 2015.0 - 2020.0. The API wraps the original WMM code. Amentum Pty Ltd is not responsible nor liable for any loss or damage of any sort incurred as the result of the use of the API. Copyright Amentum Pty Ltd 2019.