AG-UI
Open event-based protocol that connects any agent backend to any user-facing frontend or chat UI.
About
Rather than every agent framework inventing its own chat UI wiring, AG-UI defines a shared vocabulary: roughly 16 standard event types that stream from any agent backend to any frontend over SSE, WebSockets, or webhooks. The protocol, created by the CopilotKit team, covers token-by-token message streaming, tool calls rendered as typed UI components, bidirectional state synchronization via event-sourced diffs, and human-in-the-loop interrupts that let users approve, edit, or retry an agent's steps before they proceed. SDKs ship for TypeScript and Python plus community ports in Kotlin, Go, Dart, Java, Rust, Ruby, C++, and .NET, and integrations exist for Microsoft Agent Framework, Google ADK, AWS Strands Agents, LangGraph, CrewAI, Pydantic AI, Agno, LlamaIndex, and Mastra. An interactive Dojo site demonstrates each capability with code walkthroughs. Everything is MIT licensed with no hosted dependency, so the protocol works equally with API models or local ones, and the repo has passed 15,000 GitHub stars.
Should you use AG-UI?
Pick it when
Pick AG-UI when you are building your own agent frontend and want the backend to stay swappable, for example a LangGraph or CrewAI agent today and Google ADK later, without rewriting the streaming, tool-call, and approval wiring each time.
Look elsewhere when
Skip it if you just want a working chat screen: AG-UI is a protocol, not components, so you still build the UI. CopilotKit or assistant-ui give you ready React parts, and Open WebUI or LibreChat give you a finished app.
Alternatives to AG-UI
- CopilotKit
Built on AG-UI by the same team and ships ready React components and hooks, so less to build, but you adopt a full framework instead of a thin protocol.
- assistant-ui
Finished React chat primitives with Vercel AI SDK and LangGraph adapters, but it is a UI library, not a cross-language event standard for any frontend.
- Vercel AI SDK
TypeScript toolkit with its own streaming format plus chat hooks for React, Vue, Svelte, and Angular, simpler for an all-TypeScript stack, but not a cross-language event standard.
- Chainlit
Python only with a prebuilt chat frontend, so much faster to a demo, but you get Chainlit's UI rather than a protocol you can render anywhere.
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Details
- Category
- UI & Chat Interfaces
- Price
- Free
- Platform
- Local/Desktop
- Difficulty
- Intermediate (3/5)
- License
- MIT
- Added
- Aug 24, 2026