Senior Mobile Developer (iOS/Android) - SDK & Platform (all genders)

Your Mission: Shape the Future of Retail Experiences At GK – a global leader in retail technology and part of the Fujitsu Group, specializing in checkout, store operations, and customer experience – you’re not here to maintain the status quo — you’re here to disrupt, innovate, and elevate. We build the SDK-based building blocks that let our partners and customers assemble their own individual apps on top of our platform. As a Senior Mobile Developer, you’ll shape the core components that power a growing ecosystem of partner and customer applications, not just a single app. Your responsibilities Design and develop SDK components and modules for iOS and Android that partners and customers use as building blocks for their own apps Define and evolve clean, well-documented public APIs for our SDK, balancing flexibility for partners with simplicity and consistency Contribute to and help shape our entire frontend stack, including cross-platform and web technologies Work with the native iOS SDK / Android SDK and programming in Swift/Kotlin (Objective-C/Java legacy knowledge a plus) Continuously evaluate new technologies, prototype them, and assess their fit for our SDK architecture Ensure quality and stability through automated tests, code reviews, and strong engineering practices, treating the SDK as a product partners depend on Proactively identify gaps, edge cases, and improvement opportunities rather than waiting to be told what to build Collaborate closely in an agile, cross-functional team, taking ownership of technical decisions and contributing ideas beyond your immediate task Your profile Completed studies in computer science or equivalent qualification, with several years of hands-on experience in Swift and/or Kotlin (Objective-C/Java experience welcome) Proven experience building or maintaining an SDK, library, or platform consumed by external developers or partner teams You understand API design, versioning, backward compatibility, and developer experience Strong know-how in client-server communication, databases, and web services Very good knowledge of iOS/Android standard frameworks, APIs, and common design patterns A quality-first mindset: comfortable writing automated tests, reviewing code critically, and pushing back on shortcuts that hurt long-term maintainability Demonstrated ability to work iteratively and proactively Conversational English; German skills advantageous Enjoy working in motivated, international, cross-functional teams and mentoring or collaborating closely with partner developers Why Join GK? Mission-driven: We simplify interactions in retail – for businesses and customers alike. Empowered by flexibility: Remote-first, flexible hours – work where and how you thrive. Security with vision: Permanent contract in a future-focused, stable environment. Culture that connects: Open, collaborative, and people-first – with great coffee if you drop by 😉 . Backed by strength: With 35+ years of retail tech expertise and as part of Fujitsu, a global IT leader. Tech that scales: AI-powered solutions built to grow with the world’s leading retailers. Think global: 570,000+ installations in 65+ countries. Real impact, worldwide.