langchain-nextjs-template

Why we included this project

This is the official LangChain team's starter template for running LangChain.js on Next.js, and it works as a reference for how a real app fits together. Each API route demonstrates one pattern: plain chat with streamed tokens, structured output from a single LLM call, multi-step agents built with LangGraph.js, and RAG against a vector store, both as a straightforward chain and with an agent driving it. Streaming to the browser goes through the Vercel AI SDK, and since the app targets serverless Edge functions, the template keeps bundle size tight enough to stay free-tier friendly. You can clone it, add an OpenAI API key, and be chatting with the bot within minutes. That makes it a practical base for internal chatbots, document Q&A, or agent-based tooling on the JavaScript stack.