Hands-on data lead. I build trustworthy AI analytics: semantic layers, guardrails, evals.

• I build: data stacks ready for agentic analytics: dbt, semantic layers, Snowflake, DuckDB/MotherDuck, Python and Dagster, plus evals to check the agents.
• Also worked with: Airflow, AWS (S3, DMS for CDC, Lambda), Iceberg, GitHub Actions, Docker, Claude Code.
• I've built: the data stack from scratch, twice (Door2door, nebenan.de), and led the data team at nebenan.de.
• Impact at nebenan.de:
  • led the personalised notifications end to end: click rates doubled, daily active users up about 24%
  • cut Snowflake ingestion costs by more than 80%
  • moved the personalisation pipelines to MotherDuck: 30% lower compute costs, near real-time
• Now: honest-agent, open-source evals that check whether your AI analytics agent got the right answer from the right sources.
• Writing: The Data Lead, on data infrastructure, analytics engineering and leading data teams.

Work with me: I've gone freelance, building data foundations and AI analytics hands-on with companies. Get in touch through The Groundlayer or on LinkedIn.