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.

Frontend Engineer

In short: We're hiring a Frontend Engineer to build performant, scalable user interfaces for our rapidly growing LLM engineering platform.

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:

• Building complex data visualization components for billions of LLM traces
• Optimizing bundle sizes and implementing code splitting for faster load times
• Creating performant table components that handle millions of rows of data
• Building real-time dashboards with WebSocket connections
• Implementing advanced filtering and search interfaces for complex datasets
• Writing comprehensive frontend tests and setting up CI/CD pipelines

Tech Stack

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

• React
• Frontend and Backend in Typescript (including Express, NextJs, Tailwind, Prisma, tRPC)
• Clickhouse, Postgres, Redis, S3

What we're looking for

• 3+ years of experience in frontend development
• Experience building high-performance web applications that handle large datasets
• Strong understanding of React, TypeScript, and modern frontend tooling
• Experience with state management and data fetching patterns
• Hard worker and thrive working in a small and accountable team
• Excited about open source software
• A CS/quantitative degree is preferred

Bonus

• Performance optimization and profiling experience
• 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

• 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