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https://github.com/langchain-ai/langchainjs

The agent engineering platform
https://github.com/langchain-ai/langchainjs

Last synced: 25 days ago
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The agent engineering platform

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The agent engineering platform.





![npm](https://img.shields.io/npm/dm/langchain) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT) [![Twitter](https://img.shields.io/twitter/url/https/twitter.com/langchain_js.svg?style=social&label=Follow%20%40LangChain)](https://x.com/langchain_js)



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.



> [!TIP]

> Just getting started? Check out **[Deep Agents](http://docs.langchain.com/oss/javascript/deepagents/)** — a higher-level package built on LangChain for agents that have built-in capabilites for common usage patterns such as planning, subagents, file system usage, and more.



**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://docs.langchain.com/oss/javascript/langgraph/overview) - our framework for building agents and controllable workflows.



For an equivalent Python library, 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



`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.

- **Rapid prototyping**. Quickly build and iterate on LLM applications with LangChain's modular, component-based architecture. Test different approaches and workflows without rebuilding from scratch, accelerating your development cycle.

- **Production-ready features**. Deploy reliable applications with built-in support for monitoring, evaluation, and debugging through integrations like LangSmith. Scale with confidence using battle-tested patterns and best practices.

- **Vibrant community and ecosystem**. Leverage a rich ecosystem of integrations, templates, and community-contributed components. Benefit from continuous improvements and stay up-to-date with the latest AI developments through an active open-source community.

- **Flexible abstraction layers**. Work at the level of abstraction that suits your needs - from high-level chains for quick starts to low-level components for fine-grained control. LangChain grows with your application's complexity.



## 📦 LangChain's ecosystem



- [Deep Agents (JS)](https://docs.langchain.com/oss/javascript/deepagents/overview) - Build agents that can plan, use subagents, and leverage file systems for complex tasks. A higher-level package built on top of LangChain.

- [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.

- [LangSmith Deployment](https://docs.langchain.com/langsmith/deployments) — Deploy and scale agents with a purpose-built platform for long-running, stateful workflows

- [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.

- [Integrations](https://docs.langchain.com/oss/javascript/integrations/providers/overview) — Chat & embedding models, tools & toolkits, and more



## 🌐 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/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 [`CONTRIBUTING.md`](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).