Holger Krekel
CTO at merlinux
Freiburg im Breisgau, Baden-Württemberg, Germany
Summary
🤩
Rockstar🎓
Top SchoolHolger Krekel is a seasoned CTO and founder with 23 years in software engineering, and over a decade of professional Python experience rooted in a lifetime of hacking and computing. He co-initiated PyPy and originated widely used testing tools like pytest and tox, combining deep language/runtime insight with practical developer tooling. As founder and technical lead at merlinux since 2004 he has delivered large international projects while remaining hands‑on in backend, CI/CD and test automation work. His open-source contributions span influential projects—devpi, pluggy and pytest-xdist—where he’s focused on refactoring for clarity, robustness in mirroring/replication, and advancing plugin and distributed testing infrastructures. Based in Freiburg, Germany, he blends engineering leadership with consulting for interesting technical challenges, and brings a rare mix of protocol-level expertise and pragmatic build/release engineering.
23 years of coding experience
Diplom, Information Science and Applied mathematics, Diplom, Information Science and Applied mathematics at Stiftung Universität Hildesheim
Stackoverflow
22,389reputation
1.8mreached
109answers
7questions
printing
top-1%
flags
top-1%
automated-tests
top-5%
pytest
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unit-testing
top-1%
python
top-1%
Github Skills (45)
printing10
unit-testing10
hook10
docker10
software-design10
pytest10
selenium10
python10
testing10
plugin-development10
bash10
distributed-testing10
dockers10
cicd10
refactor10
Programming languages (17)
Github contributions (5)
pytest-dev/pytest-xdist
Jan 2010 - Dec 2015
pytest plugin for distributed testing and loop-on-failures testing modes.
Role in this project:
QA Engineer / Test Automation Engineer
QA Engineer / Test Automation EngineerContributions:169 commits, 1 PR, 1 push in 5 years 11 months
Contributions summary:Holger primarily contributed to the improvement and maintenance of the testing infrastructure for the pytest-xdist plugin. The commits involved modifications to test files, adding and modifying tests related to distributed testing, loop-on-fail modes, and general test setup. These changes included fixing bugs, adapting to new versions of pytest, and enhancing test coverage by adding new tests and ensuring existing ones functioned correctly.
pythontestingdistributed-testingdummy-dataloop
devpi/devpi
Apr 2013 - Dec 2017
Python PyPi staging server and packaging, testing, release tool
Role in this project:Back-end Developer
Back-end DeveloperContributions:1311 commits, 25 PRs, 27 pushes in 4 years 8 months
Contributions summary:Holger primarily worked on refactoring the codebase, specifically renaming functions and classes to improve clarity and symmetry. They also focused on enhancing the reliability of the mirroring process, fixing issues related to the replication of files and ensuring correct handling of both project names and releases. Furthermore, the user addressed issues related to unicode character handling. These changes involved interactions with core components and database.
pythonpypistaging-servertestingpackaging
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