Professional
Rewriting MijnPensioenOverzicht.nl at Mirabeau
- Event-Driven Architecture
- Microservices
- Performance Engineering
- Stress Testing
- System Modularization
MijnPensioenOverzicht.nl is the national pension overview of the Netherlands — the system every pension provider feeds into, so that anyone living in the country can see their complete pension picture in one place. I was the lead backend engineer on the rewrite of its legacy core.
The scale and the deadline. Every change to any person’s pension information flows into this system. With more than 18 million people currently living in the Netherlands — before you even count historical records — the platform has to process the data for the entire country within a single working day. The legacy system could no longer keep up with those performance demands, which is precisely why it had to be rewritten.
Stress-testing first, not last. I convinced the teams to invest in stress testing up front rather than treating it as a late-stage check. Getting that discipline in place took real time and persistence — and it paid off: once we built the backend to our initial design, the up-front performance testing revealed it wouldn’t meet the requirements. Discovering that early, by design, is exactly the point — we learned it in a test harness instead of in a production emergency.
A redesign that beat the target by an order of magnitude. We redesigned the architecture together, and I drove a scalable, event-based design that didn’t just clear the bar but blew past it: where the requirement was one working day, we ended up processing the data for all of the Netherlands in about twenty minutes.
Fast and maintainable. Throughput usually comes at the cost of clarity — here it didn’t. We reached that performance through a deliberate system modularization and message structure that enabled high scalability alongside a focused, to-the-point implementation. The result drew a lot of positive feedback — including from the engineers I later handed the code over to, who were genuinely happy with how maintainable it was. Systems that are both highly scalable and easy to live with are exactly what I aim to build.