Build

The LangChain open source stack provides the building blocks you need to design, test, and ship agents in Python.

Choose your starting point

Deep Agents, LangChain, and LangGraph share the same stack, so choose based on how much control you need:

Deep Agents

Build agents for complex, long-running tasks. A complete agent harness with planning, subagents, a virtual filesystem, and long-term memory built in. The fastest way to start.

LangChain

A minimal, configurable agent framework. Compose exactly what you need from models, tools, prompts, and middleware.

LangGraph

Low-level orchestration for stateful, long-running agents: durable execution, streaming, memory, and human-in-the-loop.

Explore

Integrations

Connect to model providers, vector stores, retrievers, and other components.

Learn

Follow tutorials and conceptual guides for common agent patterns and use cases.

Reference

API references, error codes, release notes, and migration guides.

Contribute

Contribute documentation, code, and integrations to the LangChain ecosystem.