langchain-ai/langchain

LangChain solves the problem of integrating LLMs with diverse data sources and external systems by offering a vast library of integrations and a modular architecture. It also addresses model interoperability, allowing developers to swap models easily, and provides production-ready features like monitoring and evaluation through LangSmith.

Developers can build a wide range of LLM-powered applications, from simple chatbots to complex multi-agent systems with planning, subagents, and file system usage via Deep Agents. Real-world use cases include customer support bots, document analysis, code generation, and automated workflows. The ceiling is high, enabling production-grade, stateful, and long-running agent workflows with LangGraph and LangSmith.