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.

Langfuse is looking for a founding fullstack engineer to join the founders. We are building open-source observability and product analytics for LLM applications and have raised a $4M Seed Round from Y Combinator, Lightspeed, La Famiglia and angels. We are now looking for our first hire, a founding full-stack engineer, to join our team in-person in Berlin (Germany).

What you will be working on

This is the perfect role for an engineer with an entrepreneurial mindset. On a normal day, you may be:

• scoping and developing new features that will be shipped to production in the coming days and weeks.
• working on improving the stability of our existing offering
• supporting and engaging with engineers using and onboarding to the Langfuse product
• driving forward the implementation of a new design language in our frontend
• sharing your work and content about Langfuse’s product with our community through blog posts, videos or in our Discord community

Stack: Frontend and Backend in Typescript (T3 Stack including NextJs, Tailwind, Prisma, tRPC), 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 will lie at the foundation of our product. As such choosing scalable technologies and anticipating upcoming challenges are key while we will continue to move quickly and iterate towards product-market-fit.

You will contribute to a thriving commercial open source project. You will have the opportunity to own parts of the Langfuse product end-to-end and take on manager responsibilities if you so choose.

Who We Are Looking For?

We are looking for a fullstack engineer. Someone who is looking to wear a number of hats at the same time or start a company themselves in the future.

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

• You are a hard worker and thrive working in a small and accountable team
• You want to take ownership in building out significant parts of a growing product
• You are excited about open source software and want to talk to our users to understand them and their use cases better
• You have demonstrated experience in full-stack development - a CS/quantitative degree is preferred
• Your architectural and tool choices suit the company stage, the features that have to be built now or in the future, and team experience.
• You have impressive achievements from previous careers and from side projects — we’re excited to hear about these!

Bonus Points

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

Team, Values & Benefits

You will be the first to join the three founders of Langfuse: Max (CTO), Marc (CEO) and Clemens (COO). We are a complimentary team with diverse experience ranging from technical to commercial.

We work in-person from our lovely office in the heart of Berlin-Mitte. We aim for 3-5 days in the office a week and regular shared lasagna meals, beers, Mario Kart and other fun stuff.

You will receive a competitive package of salary and equity. We are happy to discuss your preference between the two. Please find guidance below.

Salary & Equity Ranges

Salary: 60,000 - 100,000 EUR

Equity: 0.1% - 1.5% Equity

https://github.com/langfuse/langfuse/

Stack: Frontend and Backend in Typescript (T3 Stack including NextJs, Tailwind, Prisma, tRPC), Postgres, Client facing SDKs in Python and Typescript