Johannes Hertenstein
Freelance Software Developer DevOps Engineer at j6s.dev
Freiburg im Breisgau, Baden-Württemberg, Germany
Summary
👤
Senior🎓
Top SchoolJohannes Hertenstein is a freelance software developer and DevOps engineer with 12 years of hands-on experience building maintainable, scalable systems using PHP (Symfony/Laravel), Go, and TypeScript. Based in Freiburg, he blends backend craftsmanship with practical DevOps—working across Linux on devices from workstations to SBCs and deploying infrastructure with Docker, Kubernetes, Ansible/Chef and CI/CD. A measured contributor to notable open-source projects like restic and Neos, he has improved core caching and CLI usability, showing attention to performance and developer ergonomics. Johannes treats software as a long-term craft, prioritizing refactoring and sustainable architectures that reduce technical debt. He’s equally comfortable diving into low-level system details and modern cloud workflows, often uncovering subtle inefficiencies that others overlook.
12 years of coding experience
9 years of employment as a software developer
Bachelor of Science (B.Sc.), Computer Software Engineering, Bachelor of Science (B.Sc.), Computer Software Engineering at Baden-Wuerttemberg Cooperative State University (DHBW)
English, German
Github Skills (21)
deduplication10
caching10
content-management-system10
filesystem10
flowframework10
command-line-interface10
file-operations10
php10
backup10
go10
content-management10
fileio10
command-line10
cli10
testing9
Programming languages (16)
Github contributions (5)
neos/neos-development-collection
Dec 2018 - May 2019
The unified repository containing the Neos core packages, used for Neos development.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:14 commits, 2 PRs, 8 comments in 5 months
Contributions summary:Johannes primarily contributed to bug fixes and refactoring within the Neos content management system. Their work focused on optimizing node retrieval within the `NodePrivilegeContext` by preventing redundant fetching and utilizing a cache. They also migrated from a static array to an injected cache class (`TransientNodeCache`), streamlining the caching mechanism for improved performance and maintainability of node access. These changes targeted multiple versions of the Neos framework, indicating a focus on core functionality.
content-managementflowframeworkneos
restic/restic
Oct 2018 - Jan 2019
Fast, secure, efficient backup program
Role in this project:Back-end Developer
Back-end DeveloperContributions:13 commits, 5 PRs, 8 comments in 3 months
Contributions summary:Johannes primarily contributed to the `restic` project by enhancing the command-line interface and expanding the functionality of the cache command. This included adding features such as displaying directory sizes, fixing path joining, and addressing potential errors in cache directory traversal. Furthermore, the user integrated insensitive include/exclude options into the backup and restore commands and improved code documentation. Their work focused on improving usability and extending the capabilities of core backup and restore functions.
securededuperesticdeduplicationsecure-by-default
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