SAP
Corona-Warn-App
The Corona-Warn-App is Germany's official app for contact tracing and digital COVID certificates. At its peak, 38 million people used it. That makes it one of Europe's largest government-backed health apps.
The Challenge
In the late phase of the pandemic, the rules often changed at short notice. The app had to implement new requirements for vaccination and test certificates that also had to work in other EU countries. GDPR applied throughout, and the source code was public on GitHub.
The Approach
I worked in the iOS stream of a 27-person team coordinated by SAP. I built features in Swift and maintained the codebase. Apple's Exposure Notification Framework and German data protection law set the rules. Unit and UI tests with XCTest cover 90% of the code. We coordinated updates closely with backend, QA and regulatory stakeholders, often under time pressure from new public health rules.
An app used by 38 million people during a critical public health period.
Impact & Results
At its peak, 38 million people used the app. I took it through the rule changes of the late pandemic up to its controlled shutdown.
My Role
Senior iOS Engineer responsible for feature development, bug resolution, and code quality within the iOS stream. Participated in architecture discussions and code reviews in a highly regulated, open-source environment under public scrutiny.
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