LangChain.js
LangChain.js is a TypeScript framework for building LLM-powered applications, providing standard interfaces for agents, models, embeddings, vector stores, and more. It simplifies AI app development by chaining interoperable components and third-party integrations, and supports multiple JavaScript environments. It is for developers who want to build, prototype, and deploy LLM applications with flexibility and production-ready features.
✨ Key features
- Standard interfaces for agents, models, embeddings, vector stores
- Real-time data augmentation with diverse data sources
- Model interoperability: swap models easily
- Rapid prototyping with modular component-based architecture
- Production-ready features with LangSmith integration
- Flexible abstraction layers from high-level chains to low-level components
🎯 Use cases
- Build chatbots and conversational agents
- Create retrieval-augmented generation (RAG) applications
- Develop tools that connect LLMs to external APIs and data sources
- Prototype and iterate on LLM workflows quickly
- Deploy LLM applications with monitoring and evaluation
📦 Installation
🧰 Requirements: Requires Node.js 20.x, 22.x, or 24.x (or other supported environments like Cloudflare Workers, Vercel/Next.js, Deno, Bun). No API keys required for installation, but using models requires provider keys.
npm install -S langchainpnpm install langchainyarn add langchain🚀 Usage
import { ChatOpenAI } from "langchain/chat_models/openai";
const model = new ChatOpenAI({ model: "gpt-4" });
const response = await model.invoke("Hello, how are you?");
console.log(response);
❓ FAQ
What is LangChain.js?
LangChain.js is a TypeScript framework for building LLM-powered applications, providing standard interfaces and integrations to simplify development.
What environments does LangChain.js support?
It supports Node.js (ESM and CommonJS) versions 20.x, 22.x, 24.x, as well as Cloudflare Workers, Vercel/Next.js, Supabase Edge Functions, browser, Deno, and Bun.
How do I install LangChain.js?
You can install it via npm, pnpm, or yarn: npm install -S langchain, pnpm install langchain, or yarn add langchain.
What is the relationship between LangChain.js and LangGraph.js?
LangGraph.js is a separate framework for building agents and controllable workflows, built on LangChain.js for more advanced customization and orchestration.
📊 Repository
🤖 Overview, features, install steps and FAQ were generated from the project's README on Sep 4, 2026. Always check the original source before running commands.