Open source LLM engineering platform

Product Engineer

€70K - €130K EUR / 0.25% - 0.75%
Berlin, BE, DE
Job Type
3+ years
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Clemens Rawert
Clemens Rawert

About the role


Langfuse is building open source dev tooling for LLM apps based on observability/tracing. We have significant traction, are growing fast. We are looking for a full stack product engineer to help us build out our platform in Berlin, Germany.

About Langfuse

Langfuse is building the open-source LLM engineering platform. We help engineers understand how users interact with their LLM applications and how they can improve them. Have a look at our website, our GitHub and especially our technical docs to learn more.

We have raised a $4m seed round from Y Combinator, Lightspeed and General Catalyst. Thousands of engineers use Langfuse to observe, debug and improve their LLM apps. We are now looking for a hands-on product engineer  to join our team in-person in Berlin, Germany.

What you will be working on

Your main responsibility will be to add new features and build out existing ones in Langfuse. At the core of Langfuse lies the ingestion of millions of events a day via our SDKs. Once the data is in our database, we visualize it in our UI and run async workflows on top of it in the background.

You will be working closely with Max (CTO) and Marc (CEO) who own tech and product respectively.

Projects we have worked on in the past that you would have been involved in:

  • Our first launch week
    • You would have owned one of the larger features we released
    • You would have tested it with users and prepared documentation and content
    • You would have owned iteration and fixes based on user feedback and data
  • The build out of our model-based evals feature
  • Rolling out the LLM Playground and connecting it to other parts of the product
  • Maintaining our core integrations (Llama Index, Langchain, OpenAI) and introducing new ones (such as our Posthog Integration)
  • For a fuller picture have a look at our changelog

Stack: Frontend and Backend in Typescript (T3 Stack including NextJs, Tailwind, Prisma, tRPC), Clickhouse, Postgres, Client facing SDKs in Python and Typescript, — you should be familiar with a majority of these but we trust that you can pick up a new language/framework quickly. Please have a look at our repo to see our architectural choices.

The opportunity

You are joining Langfuse early. We will treat you as a core member of the team from day 1 and you will be incentivized as such. Your decisions and code lie at the foundation of our product. Choosing appropriate yet scalable technologies and anticipating upcoming challenges are key.

You will contribute to a thriving commercial open source project and build in public. You will own parts of the Langfuse product end-to-end. You may decide to take on manager responsibilities over time if you so choose.

Who We Are Looking For?

This is the perfect role for an experienced engineer that wants to join an early stage company and build it into the leading open source LLMOps platform.

  • You are a hard worker and thrive working in a small and accountable team
  • You want to take ownership in shipping features for a fast growing devtool
  • You are excited about open source software. You want to talk to our users to understand why they use us and what they require.
  • You have 2+ years of experience in full-stack development
  • You have impressive achievements from previous careers and from side projects — we’re excited to hear about these!

Bonus Points

  • Experience with or interest in UX/UI design and DX
  • You’ve started a company before or worked at a very early stage startup
  • ML/AI experience

Team, Values & Benefits

You will join our early core team and work closely with the three founders of Langfuse: Max (CTO), Marc (CEO) and Clemens (COO) and our two engineers Marlies and Hassieb.

We work in-person from our lovely office in the heart of Berlin-Mitte. You must be willing to be located in Berlin. We aim for 3-5 days in the office a week.

Our team culture is built around performance and learning. We want to build a small team of highly motivated, independent and intelligent people. We will support and challenge you while granting you a high degree of autonomy.

A few tidbits that might help you understand what kind of company we are:

  • We plan on only hiring engineers for the foreseeable future
  • You can expect to have ~1 meeting a day on average
  • Reed Hastings’ ‘No Rules Rules’ inspires our culture, here’s a summary
  • We’re big fans of Y Combinator and follow its ethos. We’re a Silicon Valley Startup in Berlin - more here

About the interview

  • Intro Call - Intro, Logistics & Fit with a founder (30min)

  • Second Call - Get to know Product and Tech at Langfuse with a founder (40min)

  • Third Call - Technical Interview: Coding challenge and Systems Design (90min)

  • On-site Super Day (0.5-1 day)

    • We will get together in our office in Berlin and work together on a real problem for a day.
    • This will include discussing the problem, scoping a solution and implementing a solution (or a solution sketch) and releasing it on our open source repo the same day.

  • Decision

We expect you to have used Langfuse (you can sign up for a free account here) and skimmed through our documentation and public content.

About Langfuse

Langfuse is building open-source observability and product analytics for LLM applications. We help engineers and companies understand how customers use their LLM applications and how they can improve on them. Have a look at our website and especially technical docs to learn more.

Team Size:5
Location:Berlin, Germany
Maximilian Deichmann
Maximilian Deichmann
Marc Klingen
Marc Klingen
Clemens Rawert
Clemens Rawert