LangSmith (LangChain)

About LangSmith (LangChain)

LangChain was founded in 2022 by Harrison Chase and quickly became the most widely adopted open-source framework for building LLM-powered applications. The library abstracts the complexity of working with different LLM APIs, vector databases, retrievers, and agent tools behind a unified interface, enabling developers to compose complex AI workflows from modular components. LangSmith is LangChain's commercial product—a cloud platform for LLM application observability, evaluation, testing, and deployment. As LLM applications move from prototype to production, teams need visibility into exactly what prompts are sent, what responses are returned, where errors occur, how latency is distributed, and whether outputs meet quality standards. LangSmith provides all of this: traces of every LLM call in a chain or agent, automated evaluation against ground-truth datasets, A/B testing of prompt variations, and deployment of prompt templates and chains as managed services. For enterprise teams building production AI applications with LangChain, LangSmith is the natural operational layer. The platform supports annotation workflows for human feedback collection, custom evaluators for domain-specific quality metrics, and integrations with CI/CD pipelines for automated regression testing of AI outputs. LangChain Inc. is incorporated in the United States (California) and LangSmith's cloud product processes trace data, prompts, and LLM outputs on US infrastructure. For European businesses deploying LangChain applications, LangSmith's cloud product requires GDPR transfer mechanisms if traces contain personal data. The open-source LangChain framework itself can be used entirely on-premise. LangSmith Enterprise offers self-hosted deployment options for organisations with data residency requirements, which is the appropriate path for EU regulated industries.