ModelRefs / Langfuse — AI Glossary
Langfuse — AI Glossary
An open-source LLM observability platform providing tracing, evaluation, prompt management, and cost analytics.
Overview
Langfuse (2023) is an open-source (self-hostable) alternative to LangSmith supporting any LLM framework. Features: structured traces with span nesting, prompt versioning, LLM-as-judge evaluations, cost analytics by model/user/session, and datasets for regression testing. SDK clients for Python, JS/TS; HTTP API for any language.
Reference details
| Topic | infrastructure |
|---|---|
| Last reviewed | 2026-06-24 |
Related terms
Commonly confused with
One of several LLM observability platforms with heavily overlapping feature lists — tracing, evaluation, prompt management, cost analytics — which makes the comparison a deployment question rather than a feature one. The distinguishing axis here is that it is open-source and self-hostable, so it is usually the answer when trace data cannot leave your infrastructure. Compare with LangSmith, Braintrust and Phoenix on that basis first.
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Frequently asked questions
What is Langfuse?
An open-source LLM observability platform providing tracing, evaluation, prompt management, and cost analytics.
What concepts are related to Langfuse?
Closely related concepts include langsmith, tracing, arize phoenix.