Google + CopilotKit

Let AI Agents
Safely Generate UI

A2UI is an open declarative UI protocol that enables AI agents to safely render rich interactive interfaces across platforms without executing arbitrary code.

Get Started Documentation

🏷️

v0.8

Current Version

📜

Apache 2.0

Open Source

⚡

Frameworks

a2ui-response.json

🔒Secure Declarative

⚡Streaming Render

🔄Cross-platform

Core Features

Four Core Features

Built for AI-era UI interactions, solving secure rendering across trust boundaries

Security First

Security by Design

Uses declarative data format, not executable code. Agents can only use pre-approved components, eliminating UI injection attack risks at the architecture level.

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LLM Friendly

LLM-Friendly Format

Flat JSON structure optimized for LLM token-by-token generation. Adjacency list model supports efficient parsing and incremental updates.

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Framework Agnostic

The same A2UI response can be rendered on React, Angular, Flutter, or native mobile platforms using each platform's native components.

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Progressive Rendering

Supports streaming UI updates, users see the interface build progressively in real-time. Instant response, natural experience.

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How It Works

A2UI enables secure communication between AI Agents and clients through a declarative protocol

💬

STEP 01

User Sends Message

User sends a request to the AI Agent, e.g., "Find nearby restaurants"

🤖

STEP 02

Agent Generates A2UI

AI Agent generates an A2UI message describing the UI (JSON format component tree)

📡

STEP 03

Streaming

Message streams to client, supporting render while generating

🎨

STEP 04

Local Rendering

Client renders UI using native components (React/Flutter/Angular)

👆

STEP 05

User Interaction

User interacts with UI, events sent back to Agent

🔄

STEP 06

Response Update

Agent responds with new A2UI message, UI updates dynamically

Architecture Overview

👤

User

Request

🤖

AI Agent(Gemini, GPT...)

A2UI JSON

📱

Client(React, Flutter...)

Render

✨

Native UI

Live Demo · No Installation

Try A2UI Composer

Build and test A2UI interfaces directly in your browser with visual tools,
drag & drop components, live preview, export JSON with one click

Open Demo

🎨

Visual Builder

Drag & drop components to quickly build UI, WYSIWYG

⚡

Live Preview

Instant rendering preview, millisecond response

📤

Export JSON

One-click export to standard A2UI format

A2UI Composer

Click to open →

Click for fullscreen demo

Code Example

Code Examples

One A2UI response, native rendering on multiple platforms

1{
2  "type": "surface",
3  "surface_id": "main_content",
4  "components": [
5    {
6      "id": "card_1",
7      "type": "card",
8      "props": {
9        "title": "Italian Restaurant",
10        "subtitle": "0.5 km away",
11        "image": "https://..."
12      },
13      "children": ["rating_1", "btn_1"]
14    },
15    {
16      "id": "rating_1",
17      "type": "rating",
18      "props": { "value": 4.5, "count": 128 }
19    },
20    {
21      "id": "btn_1",
22      "type": "button",
23      "props": {
24        "label": "View Details",
25        "action": "view_restaurant"
26      }
27    }
28  ]
29}