We are currently looking for a skilled Principal App Engineer (m/w/d) with a passion to assume leadership responsibilities to support us in building the fastest & most intuitive shopping app using a brand-new tech stack onsite in Hamburg or Berlin!

As a Principal position, this role requires a high degree of autonomous working and reports directly to the Director of Engineering. You will be the primary technical lead responsible for all app teams, driving technical discussions and ensuring our solutions are robust and forward-thinking.

The App & Web Team constantly improves the App, Mobile Website and Desktop Website. These big-scale products are each visited by over 11M active users every month. The team’s focus is to provide our customers the most inspiring, convenient, intuitive, and easy-to-use shopping experience. They constantly challenge themselves to raise the bar of what is “state of the art” in customer-facing products.

What you will do

• Build and maintain a high-quality mobile application using Flutter for iOS and Android platforms
• Participate as a solution architect from the very beginning of new projects; you will not just implement changes but think them through deeply and be responsible for the implementation across all stacks.
• Gain significant exposure to other teams, such as Shop Backend and Webstacks, to align solutions and drive the tech stack of all teams forward.
• Drive technical discussions forward with the team and lead architectural alignment.
• Lead by example and set coding standards, review pull requests and mentor other engineers in the team.
• Empower the team to deliver mission-critical features in quality & time.
• Contribute to architectural decisions across multiple stacks.
• Closely collaborate with Product Managers, Designers, Testers and other stacks (Backend and Web).
• Introduce new technologies, tools or processes that improve developer productivity and product quality.
• Debug performance and reliability issues across the stacks.

Who you are

• 8+ years of programming experience, with at least 3 years of native or hybrid App development experience.
• Expert-level Dart & Flutter knowledge.
• CI/CD experience – Google Play Store, App Store deployments (fastlane, GitHub Actions or similar)
• Experience with Unit and Golden Tests.
• Experience of performance optimisation and profiling (using Flutter DevTools).
• Mobile native experience – iOS or Android.
• Experience with monitoring tools – Firebase Crashlytics, Sentry, DataDog etc.
• Figma knowledge.
• Experience using AI (e.g. Copilot or Cursor) to speed up coding experience.
• Experience with Backend development.
• Mobile automated testing.
• Excellent problem-solving: You can solve conceptual, non-standard problems and exercise solid judgment based on analyzing multiple sources of information.
• High autonomy and ownership: You are motivated, take matters into your own hands, and can lead a complex project or process with little oversight from your manager.
• Strong communicator: You can communicate transparently, honestly, and effectively with both technical and non-technical stakeholders (e.g. Product, Design).
• Team player: You actively share knowledge, inspire other team members, and aim to fulfill team goals.

Nice to have

• Experience in Web Development
• DevOps experience (e.g. CI/CD pipelines, AWS)
• gRPC experience
• Firebase experience
• Open-source experience