????️???? LangChain.js

npm

LangChain is a framework for building LLM-powered applications. It helps you chain together interoperable components and third-party integrations to simplify AI application development — all while future-proofing decisions as the underlying technology evolves.

Documentation: To learn more about LangChain, check out the docs.

If you're looking for more advanced customization or agent orchestration, check out LangGraph.js. our framework for building agents and controllable workflows.

[!NOTE] Looking for the Python version? Check out LangChain.

To help you ship LangChain apps to production faster, check out LangSmith. LangSmith is a unified developer platform for building, testing, and monitoring LLM applications.

⚡️ Quick Install

You can use npm, pnpm, or yarn to install LangChain.js

npm install -S langchain
# or
pnpm install langchain
# or
yarn add langchain

???? Why use LangChain?

LangChain helps developers build applications powered by LLMs through a standard interface for agents, models, embeddings, vector stores, and more.

Use LangChain for:

Real-time data augmentation. Easily connect LLMs to diverse data sources and external/internal systems, drawing from LangChain’s vast library of integrations with model providers, tools, vector stores, retrievers, and more.
Model interoperability. Swap models in and out as your engineering team experiments to find the best choice for your application’s needs. As the industry frontier evolves, adapt quickly — LangChain’s abstractions keep you moving without losing momentum.

???? LangChain's ecosystem

LangSmith - Unified developer platform for building, testing, and monitoring LLM applications. With LangSmith, you can debug poor-performing LLM app runs, evaluate agent trajectories, gain visibility in production, and deploy agents with confidence.
LangGraph - Build agents that can reliably handle complex tasks with LangGraph, our low-level agent orchestration framework. LangGraph offers customizable architecture, long-term memory, and human-in-the-loop workflows — and is trusted in production by companies like LinkedIn, Uber, Klarna, and GitLab.
Deep Agents - Build sophisticated "deep" agents that go beyond simple tool-calling loops. Deep Agents combines planning tools, sub-agent spawning, file system access, and detailed prompts to handle complex, multi-step tasks — inspired by applications like Claude Code and Deep Research.

???? Supported Environments

LangChain.js is written in TypeScript and can be used in:

Node.js (ESM and CommonJS) - 20.x, 22.x, 24.x
Cloudflare Workers
Vercel / Next.js (Browser, Serverless and Edge functions)
Supabase Edge Functions
Browser
Deno
Bun

???? Additional Resources

Getting started: Installation, setting up the environment, simple examples
Learn: Learn about the core concepts of LangChain.
LangChain Forum: Connect with the community and share all of your technical questions, ideas, and feedback.
Chat LangChain: Ask questions & chat with our documentation.

???? Contributing

As an open-source project in a rapidly developing field, we are extremely open to contributions, whether it be in the form of a new feature, improved infrastructure, or better documentation.

For detailed information on how to contribute, see here.

Please report any security issues or concerns following our security guidelines.

Current Tags

0.3.27 ... latest (a year ago)
0.3.2-rc.0 ... next (2 years ago)
0.2.20 ... tag-for-publishing-older-relea (2 years ago)