Roblox Engine API (Luau)
The Roblox Engine API is the in-engine scripting surface used inside experiences and Studio plugins. It is written in Luau, Roblox's typed dialect of Lua 5.1, and exposes thousands of classes including Workspace, Players, Workspace, ReplicatedStorage, ServerScriptService, DataStoreService, MessagingService, HttpService, UserInputService, RemoteEvent, and the entire 3D scene graph. This API runs inside the Roblox runtime, not as a REST surface.