ArcGIS provides a rich set of geospatial, mapping, and administrative functionality through web services that are exposed though the ArcGIS REST API. Below is an overview of the most commonly used components of the API.

Premium ArcGIS Online APIs

ArcGIS Online hosts several powerful premium services for common use cases such as geocoding and getting directions. In general these services consume service credits from your ArcGIS Online account. The premium services are:

Portal for ArcGIS API

The ArcGIS Portal REST API is hosted by either ArcGIS Online or by ArcGIS Enterprise on your own infrastructure. The ArcGIS Portal API is used for managing items such as maps, layers, and other content, as well as handling privileges and authentication for users in your organization. Common use cases for the ArcGIS Portal APIs include working with users, groups, and items and accessing the search API.

ArcGIS Server REST API

The ArcGIS Server REST API allows you to work with services you have published to either ArcGIS Enterprise or ArcGIS Online. For example, when you import data into ArcGIS Online, a Feature Layer is created that is hosted on an instance of ArcGIS Server. You can then access your layer with the ArGIS REST API provided by ArcGIS Server. There are many types of layers and services provided by ArcGIS Server that you can create and publish with various ArcGIS tools including: