CopilotKit: An Open-Source UI Toolkit for Agents

CopilotKit (30k stars, MIT) is an open-source React component library for building the UI layer of AI agent applications.

Key features include:

• UI component offerings: Provides React building blocks for chat interfaces, streaming, tool calls, Human-in-the-loop (HITL), and Generative UI.
• AG-UI protocol support: Enables horizontal scaling that isn't tied to a specific framework, via AG-UI, an open protocol that works on the backend.
• Broad compatibility: Supports a wide range of agent frameworks such as LangGraph, CrewAI, LlamaIndex, Pydantic AI, and Agno, allowing developers to implement the UI while keeping their existing agents, models, and backends intact.

With this, developers can solve the complex state synchronization and streaming implementation challenges of agent frameworks, and quickly build a consistent user experience across different environments.