MLflow
MLflow is an open-source platform for managing the full ML lifecycle, now extended with native LLM tracking and tracing. It captures prompts, responses, latency, and costs in MLflow Tracing, integrates with LangChain and OpenAI, and provides a unified experiment UI.
Langfuse
Open-source platform for tracing, evaluations, and prompt management. Self-hostable alternative to LangSmith with clean UX.