CopilotKit

CopilotKit supplies the frontend layer for agent-native applications: React components and hooks that connect an agent backend to in-app chat, generative UI, shared state, and human-in-the-loop approval flows. CopilotChat and CopilotTextarea drop AI assistance into existing interfaces, agents can render live React components instead of plain text, and the useAgent hook synchronizes state in both directions between the UI and frameworks like LangGraph, CrewAI, Mastra, and PydanticAI. The project also maintains AG-UI, an open protocol for agent-user interaction adopted by Google, LangChain, AWS, Microsoft, and others, positioning it as a standard bridge between agent backends and user interfaces. React and Next.js support is GA, with Angular, Vue, and React Native also covered; projects scaffold with npx copilotkit@latest create and the runtime self-hosts on Node with no GPU involved. The MIT license keeps the framework free, while the optional Copilot Cloud platform adds a managed intelligence layer. With 36.4k GitHub stars it is one of the most used open source toolkits for putting agents in front of end users.