Senior React Native Developer for Long-Term Fitness App Takeover

ATLETICA is a fitness equipment brand with operations in Germany and the United States. Alongside our core hardware business, we run a strength training mobile app for our customers — live on iOS and Android with an active user base. We are looking for a senior React Native developer to take over the ongoing development of this app on a long-term basis. Contract-to-hire is on the table for the right person. What we need: A reliable React Native engineer who can take operational ownership of our existing app — bug fixing, feature delivery, store releases, and continuous improvement. The app is React-based (React Native on mobile) with a separate backend and a web admin panel. The app is a complementary product to our equipment line, not our core business — but we treat it seriously and expect it to run smoothly. You will work directly with our product lead. You will become our long-term "internal" developer for our app solution. What you will be doing: - Bug fixing and performance improvements across iOS and Android - Feature development from spec to release - App Store Connect and Google Play Console release management - Cloud infrastructure ownership and consolidation — during onboarding, migrating hosting and credentials into ATLETICA-owned accounts where they are not yet - Ongoing infrastructure and platform health - Operational ownership of our production app You should have: - 5+ years of professional mobile development experience - Strong React Native expertise — ideally including bare React Native, not just Expo - Strong JavaScript and TypeScript skills - Working knowledge of native iOS (Swift) and Android (Kotlin) for native module work and platform-specific debugging - Demonstrable experience taking over existing React Native production codebases from previous developers - Solid backend awareness — REST APIs, database migrations, server-side logic - AWS infrastructure experience — our target cloud stack - Cloud infrastructure migration experience — moving an app from one provider account to another with no downtime - App Store Connect and Google Play Console release experience - Comfort with error monitoring tools like Sentry - Fluent English (written and verbal) — communication will be in English Strong plus: - Experience with fitness, health, or training apps - Video streaming and asset delivery experience — we have video-heavy content - Shopify API integration experience - Multi-language app architecture (i18n) - Familiarity with Firebase — the current setup may still include Firebase components that need to be understood during the handover - DSGVO and EU data protection awareness - Experience migrating between React Native versions How we work: - Weekly written status updates with clear deliverables - Async-first communication, video calls when needed - Realistic estimates — you tell us what you don't know - Documentation is part of the job, not an afterthought - Self-starter mentality — we will not micromanage; we expect you to take ownership, close loops, and flag blockers Engagement model: - Hourly contract with weekly hour cap, paid via Upwork - Initial 8 to 16 hour paid trial task before the long-term contract - 60-hour probationary period within the long-term contract How to apply Please reply with: 1. Two or three concrete example of a React Native app takeover you have done. Tell us honestly what your first 4 weeks on that project looked like — including the parts that did not go well. 2. Your expected weekly availability for the next 6 months. 3. Your honest weakest area in mobile development today. Skip cover-letter templates. Direct communication, grounded reasoning, push back when we're wrong — that's how we work. Looking forward to hearing from you.