A2UI - Google's Generative UI Spec

A2UI is Google's declarative, LLM-friendly Generative UI specification that enables agents to generate dynamic user interfaces.

What is A2UI?

A2UI is a declarative generative UI specification launched by Google. It's designed to be:

• JSONL-based - Uses JSON Lines format for streaming
• LLM-friendly - Easy for language models to generate
• Platform-agnostic - Can be rendered on any platform
• Streaming-first - Built for real-time, progressive rendering

Why A2UI?

Declarative Approach

A2UI allows agents to describe UI components declaratively, making it easier for LLMs to generate dynamic interfaces without needing to understand implementation details.

Streaming Support

Built with streaming in mind, A2UI enables progressive rendering as the agent generates responses, providing a better user experience.

Platform Agnostic

A2UI specifications can be rendered on web, mobile, or any other platform, making your agent's UI truly universal.

Using A2UI with CopilotKit

Get started with A2UI and A2A with CopilotKit

Check out the A2UI Composer to create and find widgets

Learn More

• Generative UI Specs Overview - Compare all supported specifications
• Generative UI Guide - Build with Generative UI in CopilotKit
• A2UI Site - Visit the A2UI site
• AG-UI Protocol - Learn about the protocol that supports A2UI
• Open-JSON-UI - OpenAI's alternative approach
• MCP-UI - Microsoft + Shopify's iframe-based spec