Ag Ui

The Agent User Interaction Protocol is an open, lightweight, event based protocol that standardizes how AI agents connect to user facing applications. It acts as a general purpose, two way connection between a frontend and any agent backend, defining how agent state, UI intents and user interactions flow between the model or agent runtime and the application, so developers do not have to build custom wiring for each agent. It is aimed at application developers adding agent features to their products. The protocol positions itself alongside MCP, which connects agents to tools and data, and A2A, which connects agents to each other, as the layer between agents and users. Its building blocks include streaming chat with cancel and resume, typed attachments and real time media, static and declarative generative UI, a shared state store with streamed event sourced diffs, visualization of intermediate thinking steps from traces and tool events, and frontend tool calls. First party integrations cover LangGraph, CrewAI, Microsoft Agent Framework, Google ADK, AWS Strands Agents, Mastra, Pydantic AI, Agno, LlamaIndex, AG2, the Claude Agent SDK and Oracle Agent Spec, with support for the OpenAI Agents SDK in progress. SDKs exist for TypeScript and Python, with community SDKs for Kotlin, Go, Dart, Java, Rust, Ruby, C++ and .NET. The protocol is free and open source. CopilotKit, the company that originated it, offers optional paid architecture and implementation support for production deployments, priced on request. The protocol grew out of CopilotKit's early partnership with LangChain and CrewAI, and it should not be confused with A2UI, a separate generative UI specification that works alongside it.