TL;DR
CopilotKit is a comprehensive SDK for building agent-based applications and generative UI across various frontend frameworks like React, Angular, and Vue.
Key features
Chat UI: Fully customizable chat interface supporting message streaming, tool calls, and agent responses
Backend tool rendering: When an agent calls a backend tool, UI components are rendered directly on the client
Generative UI: Agents dynamically create and update UI components based on user intent and state
Shared state: A synchronized state layer that agents and UI components can read and write in real time
Human-in-the-loop: Agents pause execution to request user input, confirmation, or correction
Self-learning (early access): Continuous agent improvement through in-context reinforcement learning (CLHF) from user feedback
When to use it
When quickly building agent-interactive UIs across platforms like web, mobile, and Slack
When developing agent applications that require generative UI or human-in-the-loop workflows
When integrating with agent backends compatible with the AG-UI protocol (e.g., LangChain, Google GenKit, Mastra)