Senior Backend Engineer (Data Infrastructure)

📍 Switzerland
📍 Germany
📍 Spain
📍 France
📍 United Kingdom
📍 Netherlands
📍 Zurich, Switzerland
📍 Munich, Germany
📍 Berlin, Germany
📍 Paris, France
📍 London, United Kingdom

EUR 90,000-160,000 per year

SENIOR

✅ Hybrid

Tech Stack
Tag name is followed by "@" symbol and proficiency level value. About proficiency levels:

1-2 — basic awareness. Minimal hands-on experience, and a rudimentary understanding of the technology's purpose;

3-6 — daily use. Comfortable and regular usage, capable of handling common tasks and challenges related to the technology;

7-9 — you are an expert, you can teach others, you know all the pitfalls and tricks;

10 — exceptional knowledge, comprehensive understanding, and adeptness in all aspects of the technology, including advanced problem-solving. Think twice before claiming or demanding such level.

AI API ClickHouse @ 4 Data Pipelines @ 4 Distributed Systems @ 7 Docker Experimentation Helm LLM Next.js OLAP @ 4 Observability @ 4 PostgreSQL Redis SQL @ 3 TypeScript @ 3

Details

Langfuse is an open-source LLM engineering platform for tracing, evaluation, and prompt management. Now part of ClickHouse, the company is building infrastructure for AI applications and processing terabytes of tracing data per day for thousands of customers.

The role focuses on owning and scaling the backend and platform infrastructure behind Langfuse, including the ingestion pipeline, ClickHouse data models and queries, backend abstractions, production environments, and self-hosting deployments. The team works across EU time zones and expects one week per month in the Berlin office.

Responsibilities

Own and optimize the ingestion pipeline from the API to ClickHouse, improving throughput, latency, reliability, and cost efficiency.
Design ClickHouse schemas, optimize merge strategies, tune batch inserts, and write and review analytical queries for dashboards and the user interface.
Build infrastructure-heavy features such as LLM-as-a-Judge, large-scale alerting, client-code execution, and batch dataset operations.
Run load tests against production data to validate schema, migration, and query optimizations.
Plan for future scale, including complex long-running agent observability and real-time evaluation.
Operate Langfuse Cloud across multiple production environments.
Support deployments ranging from a single Docker Compose setup to enterprise-grade Helm chart deployments.
Own technical areas from solution design through delivery, including proposing RFCs and shipping implementations.

Requirements

Strong backend engineering skills and an interest in database internals, query optimization, and distributed systems.
Experience with analytical databases, data pipelines, or high-throughput event processing.
Familiarity with TypeScript and SQL.
Ability to organize work independently and take ownership of technical decisions and delivery.
Interest in open-source software and willingness to discuss scaling challenges with users.
Ability to thrive in a small, accountable, engineering-focused team.
A computer science or quantitative degree is preferred.

Bonus Qualifications

Experience with ClickHouse, other OLAP databases, or observability infrastructure.
Experience building data-intensive systems at scale.
Former founder experience.

Tech Stack

TypeScript monorepo, Next.js, Express workers, PostgreSQL, ClickHouse, S3, and Redis. The backend uses Express workers for background jobs, while Redis is used for queues and caching.

Process

The company states that the full hiring process can be completed through the offer letter in less than seven days.

How the Team Works

Engineers take ownership of their areas, identify what to build, propose solutions, and ship them.
The team holds a Monday priorities check-in and a Friday demo session.
Code reviews are used for mentorship and onboarding.
The team encourages experimentation with AI tooling and workflows.