LangChain builds the infrastructure developers use to create, test, deploy, and monitor AI agents — software that can reason, plan, and take actions autonomously. The company started as a wildly popular open-source Python/JavaScript framework, then layered on three commercial products: LangChain (the workflow framework), LangGraph (a graph-based orchestration engine for stateful, long-running agents), and LangSmith (an observability, evaluation, and deployment platform). Developers use these tools to take AI prototypes to production — tracing what an agent did, evaluating whether outputs were correct, and debugging failures at scale. Customers include engineering teams at Uber, LinkedIn, and GitLab, along with thousands of enterprise software teams building internal copilots, customer support bots, and automated research tools. The company sells both a self-serve SaaS tier and enterprise contracts, with a "Deployed Engineering" motion that embeds technical staff on-site at large customers.