LangChain is an open-source framework for building AI agents that work with any language model or tool. It provides a pre-built agent architecture, so developers can assemble an agent instead of writing orchestration logic from scratch. It is aimed at software developers and engineering teams who want to prototype or ship agents quickly, from individuals experimenting with a single agent to teams building production systems.
The framework ships with templates for common use cases and implements the ReAct pattern for agent reasoning, and its library of more than a thousand integrations lets developers swap in different models, tools, and databases without rewriting an application. It runs on the LangGraph runtime, which adds durable execution with persistence, checkpointing, the ability to rewind a run, and human-in-the-loop approval steps; agents can also be extended with middleware for things like approval workflows or data filtering without touching core logic. Its broader open-source ecosystem sees more than 350 million downloads a month.
LangChain itself is an MIT-licensed open-source library that is free to use. The company behind it also sells LangSmith, a separate commercial platform for observability, evaluation, and deployment that integrates with LangChain but is not required to use the framework.
Listed 2 months ago by MakerVote editors · Updated September 2026 · 25 clicks