Senior Backend Engineer

About the Role We're looking for a Senior Backend Engineer to own and scale the infrastructure behind one of the most widely adopted open-source LLM engineering platforms in the world — processing terabytes of AI tracing data per day for thousands of AI teams, including a significant portion of the Fortune 50. We're a small, engineering-heavy team building what many consider the "Datadog" of LLM observability. We sit at the intersection of open source, high-throughput data infrastructure, and applied AI — and we're now part of a leading columnar database company, which means the engineers who built the database you'll be optimizing are a Slack message away. This is a hybrid role based in EU timezones, with approximately one week per month in our Berlin office. You can be based anywhere in the EU. Visa sponsorship is not available — you must be legally authorized to work in the EU. What You'll Do Own and optimize the ingestion pipeline: Work on throughput, latency, reliability, and cost efficiency across a high-volume data pipeline that flows from our API through to a ClickHouse-backed analytics store. Make ClickHouse sing: Design and evolve schemas, write and tune complex analytical queries, and partner with ClickHouse engineers to push the limits of what's possible at petabyte scale. Build backend abstractions: Create reusable, well-documented building blocks so that product engineers can ship data-heavy features without reinventing infrastructure each time. Operate production systems: Run and improve cloud deployments across multiple production environments — handling capacity planning, incident response, and monitoring with SRE discipline. Make self-hosting effortless: Maintain and improve deployment tooling from a single Docker Compose setup all the way to enterprise-grade Helm chart deployments on Kubernetes. Contribute to open source: Everything you ship is public and immediately used by developers worldwide — participate in PR reviews, issue triage, and commu