Langfuse – Open-source observability and analytics for LLM apps
Hi HN! Langfuse is OSS observability and analytics for LLM applications (repo: https://github.com/langfuse/langfuse, 2 min demo: https://langfuse.com/video, try it yourself: https://langfuse.com/demo) Langfuse makes capturing and viewing LLM calls (execution traces) a breeze. On top of this data, you can analyze the quality, cost and latency of LLM apps. When GPT-4 dropped, we started building LLM apps – a lot of them! [1, 2] But they all suffered from the same issue: it’s hard to assure quality in 100% of cases and even to have a clear view…
Langfuse – Open-source observability and analytics for LLM apps launched on August 29, 2023 with 143 votes, #352 of 4,347 launches that month and more than 95% of that year's launches. The site was still online in September 2026, 3 years on.
In plain words
Langfuse is an open-source observability and analytics platform for large language model applications. It captures and displays LLM API calls and execution traces, allowing developers to analyze quality, cost, and latency across their applications. Built for teams developing LLM applications who need visibility into model behavior and performance monitoring.
written from the facts on this page · September 2026
From the sources
🪢 Open source agent evals & observability: Trace, evaluate, and improve LLM applications with one open platform. - langfuse/langfuse
In the maker’s words, at launch
Hi HN! Langfuse is OSS observability and analytics for LLM applications (repo: https://github.com/langfuse/langfuse, 2 min demo: https://langfuse.com/video, try it yourself: https://langfuse.com/demo) Langfuse makes capturing and viewing LLM calls (execution traces) a…
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