A2UI

A2UI (Agent-to-User Interface) is an open-source protocol and set of libraries developed by Google to enable AI agents to generate rich, interactive user interfaces instead of relying solely on text-based responses. The project introduces a declarative JSON format that allows agents to describe the structure, components, and behavior of a user interface, which is then rendered by the client using its own native components. This approach separates UI intent from UI implementation, making it possible for the same agent-generated interface to be rendered across different platforms such as web, mobile, and desktop applications. A key design principle of A2UI is security, as it avoids executing arbitrary code generated by models and instead restricts output to structured data that maps to a predefined catalog of trusted UI components. The system also supports incremental updates, allowing agents to progressively modify the interface as a conversation evolves.