Langfuse YC Application
Langfuse went through Y Combinator in the Winter 2023 batch as a B2B company. Below: what the company does, who founded it, and its application to YC, reconstructed question by question in the real YC form.
- YC batch
- Winter 2023
- Industry
- B2BEngineering, Product and Design
- Team size
- 19
- Status
- Acquired
- Launched
- 2023
Founders
Marc KlingenCo-Founder & CEO
Maximilian DeichmannFounder
Clemens RawertFounder
What Langfuse does
Traces, evals, prompt management and metrics to debug and improve your LLM application. Onboard via Langfuse helps you build and improve LLM applications across the entire lifecycle: - Develop: Observability, Langfuse UI & Prompt Management - Monitor: Traces, Analytics, Metrics & Evaluations - Test: Experiments, Releases & Datasets We are hiring: Langfuse was acquired by Clickhouse in January of 2026.
Langfuse's YC application, reconstructed
Y Combinator application
Langfuse, Winter 2023 batch. The real form questions, answered from public data.
- Founders2
- Company7
- Progress7
- Idea4
- Equity3
- Curious2
- Batch Preference1
Company
Langfuse
Open source LLM engineering platform
We built Langfuse to help developers build, monitor, and improve applications that use large language models. Our platform provides observability with traces, prompt management tools, metrics, and evaluation capabilities. It supports the entire LLM app lifecycle: development through prompt management, monitoring via analytics and metrics, and testing with experiments and datasets.
We live in Berlin, Germany and the company is based here. After YC, we would continue to operate out of Berlin.
Berlin is where all three founders live and work. The city has a strong tech scene and is where we've built our early product and user base, so it makes sense to stay here.
21 more answers in the full application
Founders, Progress, Idea, Equity, Curious, Batch Preference are in the full version. Create a free account to open it in YC Insights, next to every other YC batch.
Frequently Asked Questions
Is this the real Langfuse YC application?
No. Y Combinator keeps submitted applications private. This is a reconstruction: the real YC form questions, answered from Langfuse's public data (launch notes, founder backgrounds, product description). It shows how a company like Langfuse would present itself to YC, not the text they submitted.
What YC batch was Langfuse in?
Langfuse was part of the Y Combinator Winter 2023 batch.
Who founded Langfuse?
Langfuse was founded by Marc Klingen, Maximilian Deichmann, Clemens Rawert.
What does Langfuse do?
Open source LLM engineering platform
How do I read the full reconstructed application?
Create a free Round Funded account. The full 26-answer version of Langfuse's application, and every other YC batch, is in YC Insights.
