Langfuse

Langfuse is an open-source LLM engineering platform founded in 2022 and headquartered in Berlin, Germany. The company was co-founded by Clemens Rawert and Marc Klingen to provide observability and development tooling for teams building applications on top of large language models.

The platform covers the full LLM application development lifecycle, including distributed tracing to debug and monitor model calls, prompt management with versioning, evaluation pipelines to assess output quality, and analytics dashboards for cost and latency tracking. Langfuse is available as a self-hosted open-source deployment or as a managed cloud service, and integrates with frameworks such as LangChain, LlamaIndex, and OpenAI's SDK.

Langfuse raised a Seed round of approximately $4 million, with backing from investors including Y Combinator, which the company participated in during the 2023 batch. The project's GitHub repository has accumulated substantial community adoption, reflecting demand for open-source observability tooling in the LLM application space. The company operates with a small team of under 50 employees.