langchain-ai/langchain

<div align="center"> <a href="https://docs.langchain.com/oss/python/langchain/overview"> <picture> <source media="(prefers-color-scheme: dark)" srcset=".github/images/logo-dark.svg"> <source media="(prefers-color-scheme: light)" srcset=".github/images/logo-light.svg"> <img alt="LangChain Logo" src=".github/images/logo-dark.svg" width="50%"> </picture> </a> </div> <div align="center"> <h3>The agent engineering platform.</h3> </div> <div align="center"> <a href="https://opensource.org/licenses/MIT" target="_blank"><img src="https://img.shields.io/pypi/l/langchain" alt="PyPI - License"></a> <a href="https://pypistats.org/packages/langchain" target="_blank"><img src="https://img.shields.io/pepy/dt/langchain" alt="PyPI - Downloads"></a> <a href="https://pypi.org/project/langchain/#history" target="_blank"><img src="https://img.shields.io/pypi/v/langchain?label=%20" alt="Version"></a> <a href="https://x.com/langchain_oss" target="_blank"><img src="https://img.shields.io/twitter/url/https/twitter.com/langchain_oss.svg?style=social&label=Follow%20%40LangChain" alt="Twitter / X"></a> </div> <br>

LangChain is a framework for building agents and 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 — 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.

Quickstart

uv add langchain

from langchain.chat_models import init_chat_model

model = init_chat_model("openai:gpt-5.5")
result = model.invoke("Hello, world!")

If you're looking for more advanced customization or agent orchestration, check out [LangGraph](https://g