Open-source tracing, evaluation and prompt management for LLM applications
Langfuse is an open-source engineering platform for LLM applications: it traces requests, records prompts and completions, tracks cost and latency, manages prompt versions, and runs evaluations against datasets. Teams use it to answer why a pipeline behaved a certain way in production, which is difficult to reconstruct from ordinary application logs. It can be self-hosted or used as a managed cloud, and SDKs cover the common Python and TypeScript frameworks. It is developer infrastructure, so it needs engineering time before it pays back.
Last updated: 2026-09-20. This site only provides an index; for exact features, pricing, and licensing, see the official website.
llm observability, prompt versioning, evaluation pipelines and production debugging
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It shows what actually happened inside an LLM call: the exact prompt sent, the response, the retrieval steps, the latency and the cost. That trace is what makes production failures debuggable.
No, there is a managed cloud. Self-hosting is common among teams with data restrictions, but it means you also operate the database and supporting services it depends on.
Tracing alone is valuable for debugging and cost control. Evaluations add the ability to compare prompt versions systematically, which is where real quality improvement comes from.
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