LangChain + Next.js Starter Template

The LangChain + Next.js Starter Template provides a robust foundation for building AI-powered applications. This boilerplate integrates LangChain.js with Next.js, leveraging Vercel's AI SDK for efficient token streaming and LangGraph.js for complex agentic workflows.

Key features and use cases demonstrated include:

• Simple Chat: Basic conversational AI using LangChain modules.
• Structured Output: Guides LLMs to return data conforming to a specific schema, utilizing OpenAI Functions and Zod for validation.
• Intelligent Agents: Develops multi-step question-answering capabilities with agents that can access external tools like the internet (via SERP API).
• Retrieval Augmented Generation (RAG): Implements RAG using a chain and a vector store (Supabase by default, but easily swappable), enabling AI to generate responses based on custom data.
• Agentic RAG: Combines agents with RAG for more dynamic and context-aware information retrieval.

The template is optimized for serverless environments, specifically Vercel's Edge functions, ensuring a small bundle size (e.g., RAG use case is under 38KB, well within free-tier limits). It utilizes LangChain Expression Language for composing modules and provides clear API routes for backend logic. Developers can quickly set up a local environment, configure API keys (OpenAI, SERPAPI, Supabase), and deploy to Vercel, making it an ideal starting point for building scalable and intelligent web applications.