assistant-ui

Composable primitives rather than a monolithic chat widget are the core idea of assistant-ui, a TypeScript and React library for building production AI chat apps. Developers scaffold a Next.js project with npx assistant-ui@latest create or add components to an existing app with init, pull pre-styled shadcn/ui theme components from the CLI, and get streaming, auto-scroll, retries, attachments, markdown rendering, code highlighting, and keyboard shortcuts handled out of the box through Thread, Message, Composer, and ActionBar primitives. Generative UI maps tool calls and JSON to custom React components, collects inline human approvals, and exposes safe frontend actions to the model. Backend integrations cover the Vercel AI SDK, LangGraph, LangChain, Google ADK, and custom data-stream endpoints, which makes it work with OpenAI, Anthropic, Google Gemini, AWS Bedrock, and local models through Ollama. The MIT-licensed library is free to self-host; an optional Assistant Cloud service adds managed thread history and storage. Backed by Y Combinator and holding 11.3k GitHub stars, it runs in production at Mastra, LangChain, and Helicone.