A practical comparison of three leading LLM observability platforms: LangSmith, Langfuse, and Opik. Covers core capabilities including tracing, cost tracking, evaluation, and prompt management. LangSmith offers the tightest LangChain/LangGraph integration and most opinionated evaluation framework but is proprietary. Langfuse is MIT-licensed, self-hostable, framework-agnostic, and backed by ClickHouse after a January 2026 acquisition. Opik (Apache 2.0) by Comet ML integrates LLM observability with traditional ML experiment tracking. Includes a feature comparison table and guidance on when to choose each tool.
Table of contents
What LLM Observability Actually MeansLangSmithLangfuseOpikComparison at a GlanceWhen to Use WhichSort: