LangSmith

Official Python SDK for LangSmith — LangChain's observability, tracing, and evaluation platform. Instruments LLM calls, chains, agents, and arbitrary functions with the @traceable decorator or wrap_openai(). Traces are sent asynchronously to LangSmith cloud (or self-hosted). Also provides dataset management and evaluation (evaluate()) APIs. Usable standalone without LangChain. Releases multiple times per week. SECURITY NOTE: CVE-2026-25528 — SSRF via baggage header injection, fixed in 0.6.3. Any version 0.4.10–0.6.2 is vulnerable.