Stef Schenkelaars
System Engineer at ZEISS Semiconductor Manufacturing Technology
Zurich, Zurich, Switzerland
Summary
👤
Senior🎓
Top SchoolStef Schenkelaars is a hands-on system engineer with 11 years of experience building and integrating complex high-tech and software systems across industries from semiconductor manufacturing to medical devices and scientific instrumentation. He founded Tracklete, a rowing training app now used by major clubs worldwide, demonstrating product-minded engineering and user-focused delivery at scale. Stef has led engineering teams as CTO and owned full project lifecycles—requirements, architecture, verification—and brings practical multidisciplinary integration skills from mechanics to software. As an open-source-minded contributor, he improved Active Storage validation testing for Rails, showing attention to robust QA and cross-version compatibility. Based in Zurich and trained in applied physics, he combines analytical rigor with entrepreneurial grit to turn ambiguous technical challenges into reliable, deployable systems.
11 years of coding experience
11 years of employment as a software developer
Master of Science (MSc) Applied Physics, Master of Science (MSc) Applied Physics at Eindhoven University of TechnologyAtheneum (V.W.O.) diploma Natuur en Techniek, Atheneum (V.W.O.) diploma Natuur en Techniek at Dongemond college
Dutch, English, German
Github Skills (12)
testing10
minitest10
data-storage10
rspec10
ruby-rails10
storage10
file-storage10
rails10
object-storage10
validation10
validations10
ruby10
Programming languages (5)
Github contributions (5)
igorkasyanchuk/active_storage_validations
Jan 2020 - Jan 2021
Do it like => validates :photos, attached: true, content_type: ['image/png', 'image/jpg', 'image/jpeg'], size: { less_than: 500.kilobytes }, limit: { min: 1, max: 3 }, aspect_ratio: :landscape, dimension: { width: { in: 800..1600 }
Role in this project:
Backend Developer & QA Engineer
Backend Developer & QA EngineerContributions:8 reviews, 18 commits, 7 PRs in 11 months
Contributions summary:Stef primarily contributed to the development of testing infrastructure for Active Storage validations. They added test matchers for validators, including dimension and content type validators, improving the test coverage and the ability to test various validation scenarios. The user also refactored and improved existing matchers and ensured that tests were compatible with different Rails versions. This involved stubbing methods and modifying the test setup to ensure accurate and reliable validation testing.
jpgwidthaspect-ratiocontent-typejpeg
Drieam/LtiLauncher
Dec 2019 - Feb 2022
An extraction layer to simplify the setup and launching of LTI tools.
Contributions:13 releases, 2 reviews, 79 commits in 2 years 2 months
extractionpythonltisimplify
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