{Tech: Europe}

Backend Engineer

About Langfuse

Langfuse is building the open-source LLM engineering platform, helping developers understand how users interact with their LLM applications and how they can improve them. Our platform enables observability and tracing for AI-driven applications. Thousands of engineers already use Langfuse to debug, optimize, and scale their LLM apps.

We have raised a $4M seed round from top investors, including Y Combinator, Lightspeed, and General Catalyst. As we continue to scale rapidly, we’re looking for a backend engineer to join our team in Berlin, Germany.

The Role: Backend Engineer

We’re seeking a backend engineer to help scale our platform and ensure its reliability. At the core of Langfuse lies the ingestion of millions of events daily via our SDKs. You’ll play a crucial role in ensuring our infrastructure is highly available, scalable, and performant.

Your Responsibilities

  • Optimize the latency of complex database queries in Postgres and Clickhouse
  • Improve self-hosted deployments by refining our Kubernetes Helm chart
  • Add Redis queues and worker containers to handle async tasks
  • Explore and implement Clickhouse as a potential alternative for our needs
  • Rebuild our SDKs for fully asynchronous networking
  • Write Terraform code to dynamically scale Langfuse containers based on custom metrics
  • Work closely with our CTO and team to ensure uptime and system resilience

What Makes You a Great Fit

  • 3+ years of experience in backend or full-stack development, with a strong understanding of handling large-scale data
  • Experience working on high-reliability and high-scale infrastructure
  • Strong knowledge of TypeScript, Node.js, Express, Next.js, Prisma, tRPC, Clickhouse, Postgres, Redis, and S3
  • Excitement for open-source development and direct user feedback
  • A hands-on, problem-solving mindset with an ability to work autonomously
  • Preference for in-person work in our Berlin Mitte office (4-5 days per week)

Bonus Points

  • Experience designing SDKs and improving developer experience
  • Background in AI/ML or working with LLMs
  • Previous startup experience or having founded a company

Compensation & Benefits

  • Salary range: €70,000 – €130,000
  • Equity range: 0.1% – 0.35%
  • Work with a high-performing, small team of engineers and founders
  • In-person collaboration in our Berlin Mitte office
  • Opportunity to contribute to a fast-growing open-source project
  • Company trips, including previous visits to San Francisco

Interview Process

  1. Intro Call (30 min) – Meet a founder to discuss logistics and mutual fit
  2. Product & Tech Discussion (40 min) – Learn more about Langfuse’s product and engineering approach
  3. Technical Interview (90 min) – Coding challenge and system design
  4. On-site Super Day (0.5–1 day) – Work on a real problem with the team in our Berlin office (travel covered if needed)
  5. Decision & Offer

We expect candidates to have explored Langfuse by signing up for a free account and reviewing our documentation.