OpenUI is an open-source framework and language for generative user interfaces. Its core, OpenUI Lang, gives language models a compact streaming format for describing structured UI so applications can render components progressively instead of treating model output as plain text or verbose JSON.

The project provides a full-stack path from component definitions and generated model instructions to streaming parsing and rendering. It includes official React support, built-in component libraries for elements such as charts, forms, tables, and layouts, chat-oriented starter interfaces, and integrations for agent frameworks and other frontend ecosystems.

OpenUI is intended for teams building assistants, copilots, and applications where the model should generate interactive interfaces as part of its response. By constraining generation to an allowed component library and using a token-efficient UI language, it aims to make generative UI more predictable, portable, and economical.