Two weeks, nationwide: how we built coronatestcenter.net

A year into the company, ThreeB IT got pulled into a corner of German healthcare we hadn't planned to be in. The COVID-19 pandemic had hit, the country needed pop-up testing centres in pharmacies, sports halls, and shopping-mall parking lots, and the operators of those centres needed software now — software that could generate compliant test certificates, integrate with the rapidly-evolving Robert Koch-Institut reporting requirements, and not collapse on a Friday at 3 PM when half of Westphalia decided to get tested before a wedding.

We shipped coronatestcenter.net end-to-end in two weeks.

What the platform did

The user journey looked simple from the outside:

1. Pre-register online. A citizen fills in a short form, picks a slot at a centre, and gets a QR code by email.
2. Walk in, scan, identify. At the test centre, the QR is scanned with an ID check — no paper form, no manual data entry, no queue.
3. Test, then certificate. The rapid test runs; the result drops back into the platform, which generates the digital test certificate the citizen needs for travel, work, or an event.

Underneath, the same platform handled appointment scheduling, walk-in capacity, daily reporting to the relevant German health authorities, and operator billing.

Why it shipped that fast

The two-week number isn't a humble-brag. It's a function of three deliberate choices the founding stack already supported:

• One language, one runtime. Front-end, back-end, document generation, scheduled jobs — all .NET. No context-switch tax.
• PDF generation via IronPDF. The first version of the certificate renderer was working within hours of adding the NuGet package; we never had to fight a HTML-to-PDF pipeline. (That's the story Iron Software ended up using as their case study; see the Excellence In Long-Term Client Partnerships award post.)
• GDPR by default. Because IronPDF runs entirely in-process with zero external data transfer, certificates with personally identifying medical information never left the operator's server — and the data-protection sign-off, which is usually the part that takes the longest in German healthcare procurement, was a non-event.

What it left behind

The pandemic eased; pop-up test centres closed; the platform was eventually wound down (coronatestcenter.net is parked now — visit it and you'll see only a sale notice).

But the lessons it left in our codebase are still working:

• The document-generation patterns from the certificate pipeline became the basis for the Kühne+Nagel customs and shipping work we'd take on later.
• The "ship in two weeks because the customer is in the middle of a real crisis" muscle is still in our institutional memory — and it informs how we scope first deliveries today.

The story is one of the reasons Iron Software named ThreeB IT the 2025 winner of their Excellence In Long-Term Client Partnerships award. That's the closure on the chapter; the platform itself sits in our institutional history as the project that proved we could ship at the speed real situations demand.