Library / SDK
Observability & Evaluation
Langfuse
1Open-source 2observability 3and 4analytics 5for 6LLMs.
the six Ws · specification
W1
Who
Open-source project with a managed cloud.
W2
What
Traces, evaluates, and monitors LLM application behavior.
W3
Where
Self-hosted or Langfuse Cloud.
W4
When
When you need visibility into production LLM apps.
W5
Why
Turns opaque agent runs into debuggable traces.
W6
With
SDK instrumentation in your application.
alternatives