CopilotKit - The Complete Frontend Stack for AI Agents

CopilotKit is an open-source frontend stack for building AI agent interfaces, with 30k+ GitHub stars and Fortune 500 adoption. It provides a three-layer architecture: a frontend layer with hooks (useAgentContext, useFrontendTool, useAgent) and prebuilt chat components, a runtime layer handling model calls and streaming, and an agent layer supporting 13+ frameworks via the AG-UI protocol. Key features include generative UI in three patterns (controlled, declarative A2UI, open-ended MCP Apps), persistent conversation threads, a built-in Inspector for debugging, headless UI primitives for custom interfaces, multimodal attachments, and a VSCode extension. It also ships an MCP server for coding agents to access up-to-date API docs, and an Intelligence Platform with analytics and continuous learning from human feedback.