Product Engineer (Growth)

Details

About Langfuse

Open Source LLM engineering platform that helps teams build useful AI applications via tracing, evaluation, and prompt management. We are now part of ClickHouse. We're building the "Datadog" of this category; model capabilities continue to improve, but building useful applications is really hard, both in startups and enterprises.

Largest open source solution in this category: trusted by 19 of the Fortune 50, >2k customers, >26M monthly SDK downloads, >6M Docker pulls.

We joined ClickHouse in January 2026 because LLM observability is fundamentally a data problem and Langfuse already ran on ClickHouse. Together we can move faster on product while staying true to open source and self-hosting, and join forces on GTM and sales to accelerate revenue. Previously backed by Y Combinator, Lightspeed, and General Catalyst.

We're a small, engineering-heavy, and experienced team in Berlin and San Francisco. We are also hiring for engineering in EU timezones and expect one week per month in our Berlin office (see handbook: how we work).

Why Growth Engineering at Langfuse

Your work will have an outsized impact. Langfuse is growing on an exponential curve while we are adding more users. Our existing users also increase their token use and build more LLM based applications and features.

We sit at the center and enable our users to build LLM applications faster, more reliably and safer.

You have real data to work with in terms of analytics and users who are the most agile and up-to-date developers building out AI applications - the perfect environment to try big bets and shape them to success. All while learning how the best agentic applications are built.

Your impact

Your work directly impacts our most important growth metrics:

• Top of Funnel: More customers want to try Langfuse
• Activation: Customers see faster time to value
• Adoption: More customers adopt all features across our product suite
• Customers require less handholding because the product explains it all
• Expansion: help customers expand from one product area to all of our offering

What you'll do

1. Understand how customers use Langfuse

• Build and maintain our data stack (PostHog, BigQuery, DBT, Metabase) to generate insights into user behavior
• Map our core funnel for each feature and make it easy to monitor (we are using PostHog for this)
• Be the advocate within the team for how customers actually adopt/use our product

2. Make our product our #1 growth engine

• Ship constant improvements that reduce onboarding friction for users
• Experiment with changes to signup flows
• Collaborate with feature-focused Product Engineers and Designers
• Build loops to help customers expand into all of our product areas

3. Build new growth engines

• Experiment with loops that make people tweet about Langfuse (e.g., like Langfuse Wrapped but better)
• Experiment with features that turn our customers' accounts into user-generated content (e.g., let customers share their prompts in Langfuse in a public prompt library)
• Jump on hot topics to integrate into Langfuse and write about it

What we're looking for

Must-haves

• Drive to learn fresh things — you experiment on many different topics and come up with ideas
• A hang for business — you envision how Langfuse succeeds through product-led growth
• Experience in full-stack development — you can ship changes that touch frontend and backend in our product with confidence
• SQL skills (for analytics)
• You are excited to talk to and think like our users

Nice-to-haves

• Experience with devtools / OSS ecosystems and developer-centric go-to-market
• Taste for UX / Design is a big plus
• Familiarity with AI/LLM engineering
• Former founders are very welcome for this role

Tech stack

We run a TypeScript monorepo: Next.js on the frontend, Express workers for background jobs, PostgreSQL for transactional data, ClickHouse for tracing at scale, S3 for file storage, and Redis for queues and caching. You should be familiar with a good chunk of this, but we trust you'll pick up the rest quickly.

How we ship

• We trust you to take ownership for your area: identify what to build, propose solutions (RFCs), and ship them. Everyone manages their own Linear.
• You're never alone: team members collaborate in whiteboard sessions and code reviews that act as mentorship.
• Maker schedule and communication: two recurring meetings a week (15-minute Monday check-in and 60-minute Friday demo).
• We use AI extensively in our workflows and encourage experimentation with new tooling and AI workflows.

Why Langfuse (now part of ClickHouse)

• This role puts you at the forefront of the AI revolution, partnering with engineering teams building foundational technology.
• This is an open-source devtools company focused on great developer experience, reliability, and performance.
• Your work ships under your name; you'll appear in changelog posts and produce materials during launch weeks.
• You'll work closely with the ClickHouse team and learn from a world-class infrastructure company.
• We're solving hard engineering problems: building SDKs developers love, visualizing data-rich traces, rendering massive LLM prompts efficiently in the UI, and processing terabytes of data per day through our ingestion pipeline.