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.

In short: We are hiring a (senior) Backend Engineer to make our systems and infra keep up with our globally growing user base and billions of monthly events to process.

About Langfuse

• We are building the fastest growing open-source LLM engineering platform.
• We help engineers and enterprises build and run LLM applications at scale.
• We've raised $4m from Y Combinator, Lightspeed and General Catalyst.
• Thousands of teams and engineers use Langfuse daily
• Thousands are joining every month
• We're a small, focused team working from Berlin, Germany.

What you'll do

Past projects you would have led:

• Optimizing the latency of complex database queries in Postgres or Clickhouse
• Adding Redis queues and a worker container to our stack to execute async tasks
• Building a POC to try out Clickhouse for our needs
• Re-building our SDKs to execute networking fully asynchronous
• Write Terraform code to scale Langfuse containers according to custom metrics

Tech Stack

You should be familiar with a majority of these but we trust that you can pick up a new language/framework quickly.

• Frontend and Backend in Typescript (including Express, NextJs, Tailwind, Prisma, tRPC)
• Clickhouse, Postgres, Redis, S3
• Client facing SDKs in Python and Typescript

What we're looking for

• Experience in maintenance of highly reliable and scaling infrastructure
• 3+ years of experience in backend or full-stack development
• Excited about open source software
• Experience with the trade offs of handling large amounts of data
• Hard worker and thrive working in a small and accountable team
• A CS/quantitative degree is preferred

Bonus

• Experience with or interest in SDK design and DX
• ML/AI experience
• Impressive achievements from previous careers or side projects
• Previous startup or founding experience

Why Langfuse?

• You are joining really early
• Strong Product Market Fit!
• We are building a very small but highly capable team
• Only hiring Engineering in foreseeable future
• Strong customer & revenue growth
• Building picks and shovels for the hottest AI companies
• Building for very sophisticated technical users
• Competitive salary & equity
• Performance and learning focused culture
• Everyone on the team says: "best place I've ever worked at"

How we work

• Engineering based in Berlin ( we aim for 4-5 days in the office )
• No more than 2 short scheduled meetings per week
• Extreme ownership & autonomy how and what to work on

Links

• Project you could have built: Infrastructure Evolution Blog Post
• Our codebase: GitHub Repository
• Ben Kuhn on Impact, Agency and Taste
• Who we are & how we work

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