LangSmith
Free tierThe end-to-end platform for building, testing, and monitoring LLM-powered applications
Free tier available·Technical·Powered by LangChain (model-agnostic)·API available
Key strengths
Deep LangChain & LangGraph integration for zero-config tracingEnd-to-end LLM observability with detailed trace visualizationBuilt-in evaluation and dataset management for regression testingPrompt management with versioning and A/B testing supportProduction monitoring with feedback collection and alerting
Free tier + paid plans
San Francisco, USA
Founded 2023
Self-hostable
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LangSmith is a full-lifecycle LLMOps platform that integrates natively with LangChain and LangGraph, providing automatic tracing of chains, agents, and tool calls with minimal instrumentation. It exposes a Python and TypeScript SDK alongside a REST API for logging runs, managing datasets, running evaluations, and triggering automated test suites in CI/CD pipelines. The platform supports both cloud-hosted and self-hosted deployments, and its evaluation framework allows developers to define custom graders or use LLM-as-a-judge scoring to benchmark prompt and model changes systematically.