FastUI is a server-driven UI system and Pydantic UI framework that transforms backend data models into functional web interfaces. It operates as a model-based frontend generator where the server controls the layout and behavior of the user interface through structured data schemas, enabling a low-code approach to web development.
The project allows for the definition of visual hierarchies and component properties on the backend, using a JSON-based protocol to communicate UI structure between the server and client. It utilizes schema-driven generation to automate the creation of interfaces, including the automatic construction of input fields and validation logic by mapping data models directly to UI components.
The framework covers a broad range of interface capabilities, including declarative layout organization, page navigation management, and data visualization via interactive tables and structured data rendering. It also provides a system for UI state and feedback, rich media embedding, and a mechanism for implementing custom UI components.