LangSmith

LangSmith is LangChain's platform for debugging, testing, evaluating, and monitoring LLM applications and AI agents in production. It traces every step of agent execution including LLM calls, tool use, and chain operations with detailed latency and cost metrics. LangSmith's evaluation framework runs automated tests against LLM outputs. Used by engineering teams building production AI agents with LangChain who need observability, debugging tools, and automated testing to ensure reliable agent behaviour and catch regressions in LLM-powered applications.