Unreal Engine C++ API
The Unreal Engine C++ API is the primary programmatic surface of the engine. It is shipped as engine source on GitHub (under the Unreal Engine EULA) and documented as a per-module class reference covering Actors, Components, GameFramework, Subsystems, Slate, RHI, Renderer, AnimGraph, Niagara, Chaos, AI, and more. Developers extend the engine by writing C++ classes and modules in their project or as plugins.