CopilotKit

CopilotKit: The Frontend Stack for AI Copilots and Agents

CopilotKit is an open-source framework for putting AI copilots and agents inside your application's user interface. Instead of bolting a generic chat widget onto an app, it gives developers React and Angular SDKs, pre-built but customizable chat components, and hooks that let an AI read app state, call frontend actions, and render generative UI — interfaces the agent produces at runtime. Its AG-UI protocol standardizes the connection between a user-facing app and agent backends built with LangGraph, CrewAI, Pydantic AI, LlamaIndex, Mastra, Agno, and others.

It is aimed at product engineering teams shipping agent-native features: you install the SDK, wrap your app in a provider, expose the state and actions the copilot should know about, and connect an agent backend over AG-UI. The same agent can then surface in the web app or in Slack, Microsoft Teams, and messaging platforms, with thread and state persistence handled for you.

Key Features

• React and Angular SDKs with pre-built, fully customizable chat and copilot components, plus headless options
• AG-UI: an open, bi-directional protocol connecting frontends to agent frameworks such as LangGraph, CrewAI, Pydantic AI, and LlamaIndex
• Generative UI — agents render live application components, not just text
• Frontend actions and shared state, so copilots can read app context and act inside it, with human-in-the-loop patterns
• Multi-surface deployment: the same agent in web, Slack, MS Teams, and messaging platforms, with thread persistence
• Open-source core with a hosted cloud and an enterprise intelligence platform on top

Ideal Use Case

A SaaS team that wants a real product copilot — one that can see the current page, fill forms, trigger app actions, and walk users through workflows — without building chat infrastructure, streaming, state sync, and agent wiring from scratch. CopilotKit handles the frontend-agent plumbing so the team's work is the agent logic and the UX.

How CopilotKit differentiates

CopilotKit's bet is the protocol layer: AG-UI has been adopted by Google, Microsoft, Amazon, and Oracle alongside frameworks like LangChain, Mastra, PydanticAI, and Agno. The company raised $27M in 2026 — a Series A led by Glilot Capital, NFX, and SignalFire on top of its seed — and the open-source repository has around 34.5k GitHub stars, with customers including Docusign and a sizable share of the Fortune 500 using it in production.

FAQ

What is CopilotKit? CopilotKit is an open-source framework for building in-app AI copilots and agent UIs, plus AG-UI, a protocol linking frontends to agent backends.

Is CopilotKit free? The core framework is free and open source; a hosted cloud and enterprise platform add paid tiers.

Which agent frameworks does it support? LangGraph, CrewAI, Pydantic AI, LlamaIndex, Mastra, Agno, and others via the AG-UI protocol.

What is AG-UI? An open, bi-directional protocol that standardizes how user-facing applications talk to agentic backends, complementing MCP and A2A.

tl;dr

CopilotKit is the open-source frontend stack for in-app copilots and agent UIs — 34.5k GitHub stars, a $27M raise, and an AG-UI protocol adopted by Google, Microsoft, Amazon, and Oracle.

Related

Looking for more options? Browse the Developer Tools directory or read our best AI coding tools listicle. CopilotKit is also tracked on Crunchbase.