For users to be able to interact with their GIS data, services, and more, Esri developed a completely new Pythonic web API called the ArcGIS API for Python, which consists of a set of subroutine definitions, protocols, and tools for building software and applications. It is built on top of the ArcGIS REpresentational State Transfer (REST) API, along with the ArcGIS API for JavaScript. This same API is also used (in the background) within the Python API for displaying 2D and 3D web maps.

GIS users can download the freely available ArcGIS API for Python and use it to manage their cloud GIS environment, whether that's ArcGIS Online, ArcGIS Portal, or ArcGIS Enterprise (the product family formerly known as ArcGIS Server). The API requires Python 3.5 or higher. It's possible to use the API together with the ArcPy site package, but this is optional, the API also works without ArcPy (or any desktop-based GIS product), or even an ArcGIS Online or Portal environment.

The API has been written for a larger audience in mind than the current Python user, who would use it for data processing or map design—apart from the scripting capabilities, the API allows for GIS visualization and analysis, spatial data/content management, as well as organization administration. The API is a work-in-progress, since its first release in December of 2006, the API has seen a number of updates and the current version is 1.4 at the time of writing. Each new release introduces new features. Using the API is similar to working with any other Python library—you import the API with an import statement and can start using it right away, applying standard Python syntax and commands. As you're using it in a web environment to access a web GIS, it's best to use the browser-based Jupyter Notebook app.