Build agents faster,
your way
LangChain is an open source framework with a pre-built agent architecture and integrations for any model or tool, so you can build agents that adapt as fast as the ecosystem evolves.
Ship fast with proven agent patterns
Build agents in minutes with templates for common use cases. create_agent provides a proven ReAct pattern on LangGraph's durable runtime.
Open and neutral by design
Swap models, tools, and databases without rewriting your application. With 1000+ integrations, you can future-proof your stack as AI advances, with no vendor lock-in.
Customize without complexity
Extend agent behavior through middleware without rewriting core logic. Add human-in-the-loop approval, compress long conversations, or remove sensitive data— all with simple, composable hooks.
Durable runtime
langchain runs on langgraph 's durable runtime — giving agents built-in persistence, rewind, checkpointing, and human-in-the-loop support.
Foundation: Introduction to LangChain - Python
Learn the basics of how to build agents with LangChain using pre-built architectures and model integrations in this LangChain Academy Course.
FAQs for LangChain
Yes - LangChain is an MIT-licensed open-source library and is free to use.
LangChain is an open source framework with pre-built agent architectures and as integrations to models, tools, and databases to start building agents quickly. The LangChain framework integrates seamlessly with LangSmith, our platform for agent observability, evaluation, and deployment — you can set just one environment variable to get started.
See what your agent is really doing
LangSmith, our agent engineering platform, helps developers debug every agent decision, eval changes, and deploy in one click.