LangChain

LangChain is a software framework that helps developers integrate large language models into applications. Its use cases largely overlap with those of language models in general, including document analysis and summarization, chatbots and code analysis. It was launched in October 2022 as an open source project by Harrison Chase, who was then working at the machine learning startup Robust Intelligence, and the company behind it was incorporated in April 2023. Later additions include the LangChain Expression Language for declaratively defining chains of actions, the LangServe deployment tool, the closed-source LangSmith observability platform, and a first major 1.0 release on 22 October 2025 that introduced a create_agent abstraction.