Hi, I’m Gerben Jongerius — a Java consultant based in Roermond, the Netherlands. I develop complex back-end systems.
I’m currently a principal consultant at Open Circle Solutions, on assignment as a Java developer at Energie Data Services Nederland (EDSN). Before that I spent several years as a Java consultant at group9, with longer assignments at ASML and APG.
Experience
I’ve been building software professionally since 2006 (~20 years). A short tour of the path on LinkedIn:
- Principal consultant — Open Circle Solutions (Mar 2025 – present); Java developer at EDSN (May 2025 – present)
- Java consultant — group9 (Jul 2018 – Feb 2025), including work at ASML (senior application engineer, 2021–2024) and APG (2018–2021)
- Lead Java developer — ENGIE Services Nederland (2015–2018)
- Java consultant — Finalist (2011–2015)
- Java developer — Inception BV (2010–2011)
- Java software engineer — GameHouse (2006–2011)
Across those roles the common thread has been Java and Spring backends: integrations, domain-heavy systems, and software that has to keep running once it’s in production—pensions, energy, semiconductors, and earlier game/platform work.
Education
Bachelor of Applied Science (BASc) in Computer Software Engineering at Fontys Hogescholen (2002–2006).
On this blog
I write about what I run into day to day: Java tooling, CI/CD and Maven releases, observability with OpenTelemetry, and yearly Advent of Code solutions in Java.
My first programming was on a Philips NMS9100 in Q-Basic. That curiosity never really stopped—it just moved from tinkering to helping teams ship maintainable systems.
Get in touch
More detail on LinkedIn and code on GitHub.