Clemens Rawert

Clemens Rawert is a co-founder of Langfuse, an open-source LLM engineering platform for tracing, prompt management and evaluation. He started it with Marc Klingen and Max Deichmann, and the company joined ClickHouse in January 2026.

Studying the Economics of New Technologies

Rawert studied economic history and some economics at Mannheim University, the London School of Economics and the University of Oxford, according to his site. His research looked at the economics of new technologies and new goods, including the printing press and the Columbian Exchange.

A Billing Startup Before Langfuse

Rawert, Klingen and Deichmann began working together in 2022. They first built Finto, a usage-based billing product aimed at problems they had met in earlier jobs, and got into Y Combinator's Winter 2023 batch with it, according to Langfuse's founding story. The three moved to San Francisco, California, for the batch. Customers liked Finto, but the founders were not excited about building another generation of product in an established, small market, and progress in large language models pointed to bigger problems.

Pivoting to LLM Engineering

During the batch the team moved through a series of AI product ideas, usually spending less than two weeks on each, and learned firsthand how hard it was to make LLM applications work reliably. That lesson became Langfuse. "Building LLM applications is hard. Many disregarded them as GPT-wrappers, but they are core to the value creation and don't just work, they need methodical evaluation and iteration," the company writes. Langfuse launched as open source, raised a $4 million seed round led by Lightspeed Venture Partners, La Famiglia and Y Combinator in September 2023, and in June 2025 opened all of its product features under the MIT license.

Opening the San Francisco Office

While most of Langfuse's engineering stayed in Berlin, Germany, Rawert moved to San Francisco and started the company's office there to work more closely with Bay Area users and customers. When Langfuse joined ClickHouse, the company said nothing changed for users: Langfuse stayed open source and the whole team joined ClickHouse to keep building it. He has also discussed the company's early path in a Cerebral Valley interview with his co-founders.

Speaking at AI Engineer Paris

Rawert has gone back to his academic roots on stage. At the AI Engineer Paris 2026 conference he gave a talk asking what economic history can teach about AI. "History doesn't necessarily repeat itself but it rhymes," his session description reads. "What does AI rhyme with? The Industrial Revolution, Printing Press, Railways, Electricity, the Internet?"