# 🦜️🔗 LangChain.js

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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](https://docs.langchain.com/oss/javascript/langchain/overview).

If you're looking for more advanced customization or agent orchestration, check out [LangGraph.js](https://langchain-ai.github.io/langgraphjs/). our framework for building agents and controllable workflows.

> [!NOTE]
> Looking for the Python version? Check out [LangChain](https://github.com/langchain-ai/langchain).

To help you ship LangChain apps to production faster, check out [LangSmith](https://smith.langchain.com).
[LangSmith](https://smith.langchain.com) 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

```sh
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](https://www.langchain.com/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](https://docs.langchain.com/oss/javascript/langgraph/overview) - 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](https://docs.langchain.com/oss/javascript/deepagents/overview) - 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](https://docs.langchain.com/oss/javascript/langchain/overview): Installation, setting up the environment, simple examples
- [Learn](https://docs.langchain.com/oss/javascript/langchain/learn): Learn about the core concepts of LangChain.
- [LangChain Forum](https://forum.langchain.com): Connect with the community and share all of your technical questions, ideas, and feedback.
- [Chat LangChain](https://chat.langchain.com): 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](https://github.com/langchain-ai/langchainjs/blob/main/CONTRIBUTING.md).

Please report any security issues or concerns following our [security guidelines](https://github.com/langchain-ai/.github/blob/main/SECURITY.md).