Hans Mooijer

Staff QA Engineer @ DeepL · Test Infrastructure & Data-driven Quality · 13+ years

Cologne, North Rhine-Westphalia, Germany

About

QA engineer with 13+ years of experience, specialising in developer experience, test infrastructure, and data-driven quality insights. I focus on making test automation work at scale across large engineering organisations: building the tooling, dashboards, and processes that give teams real visibility into quality. Lately that means a lot of SQL, Grafana, and AI-assisted development with Claude Code. I've also spent a good part of my career on the people side: building QA teams from scratch, scaling them through periods of rapid growth, and driving quality initiatives at an organisational level.

Experience

  • DeepL (13 yrs 3 mos)
    • Staff QA Engineer / Tech Lead
      Sep 2024 - Present · 1 yr 10 mos

      • Led a large cross-team initiative to review and prioritise E2E tests, reducing E2E test stage duration by 50% and cutting flaky test job duration from days to hours per week • Created 15+ Grafana dashboards and SQL-based metrics to track test suite performance across a large engineering organisation, leveraging Claude Code to accelerate development • Led a test annotation initiative across all engineering teams to capture team ownership and test type, improving visibility into test distribution and maintenance accountability • Set up a dedicated QA infrastructure team, established workflows, and provided technical guidance while continuing IC contributions

    • Team Lead QA
      Oct 2020 - Sep 2024 · 4 yrs

      ・Built the QA team from scratch, scaling to a team of 25 across a period of rapid company growth ・Established team workflows, hiring pipelines, and professional development frameworks ・Drove cross-team quality initiatives and represented QA at the organisational level

    • Dutch Language Specialist
      Apr 2013 - May 2021 · 8 yrs 2 mos

      ・Helped build and expand DeepL's Dutch-English dictionary and localisation from the early days of the product

  • Video Games Tester at Enzyme Testing Labs
    May 2012 - Jan 2013 · 9 mos

    • Carried out linguistic and functional QA testing of video games in English and Dutch, manually testing for bugs, language issues, and overall product quality.

  • Dutch Teaching Assistant at Newcastle University
    Sep 2009 - Jun 2010 · 10 mos