Backend Engineer

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
• Come up with a new architecture for our ingestion pipeline with the goal to increase throughput and cut cost
• Explore different CH schemas and materialized views and test for different query patterns.
• Re-building our SDKs to use OTEL under the hood
• Write Terraform code to add new infra components

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

1. Fill out application & We screen your application
2. Call: Intro & CV deep dive with CTO (45min)
3. Call 2: Technical Deep Dive (90min)
4. Onsite Super Day ( half or full day in Berlin Office )
5. Meet the other founders (short calls)
6. Decision & Offer

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