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" target="_blank"><img src="https://img.shields.io/twitter/url/https/twitter.com/langchain.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.

[!NOTE] Looking for the JS/TS library? Check out LangChain.js.

Quickstart

pip install langchain
# or
uv add langchain

from langchain.chat_models import init_chat_model

model = init_chat_model("openai:gpt-5.4")
result = model.invoke("Hello, world!")

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

[!TIP] For developing, debugging, an