Langfuse

Langfuse is an OpenTelemetry-native observability and evaluation platform with over 22,000 GitHub stars. It provides cost-per-feature tracking that maps directly to concepts like the Agentops Dashboard, letting teams measure exactly what each agent workflow costs. Langfuse is fully self-hostable under an MIT license, making it a strong fit for organizations building Eval Harness pipelines that need fine-grained tracing without vendor lock-in.