Freelancer Senior Mobile Engineer React in Berlin, Deutschland

Responsibilities

• Develop and evolve the easybill-mobile application for iOS and Android with React Native, Expo, and TypeScript.
• Translate invoicing and document requirements into clear mobile workflows and high-quality native interfaces.
• Develop the app architecture, navigation, reusable components, forms, and data-access structures.
• Integrate and extend API functionality, including typed interfaces, validation, caching, loading states, and error handling.
• Implement secure authentication, session management, and careful handling of sensitive customer and business data.
• Address mobile performance, platform-specific behavior, connectivity changes, accessibility, and multilingual support.
• Create automated tests and verify behavior on simulators and physical devices.
• Help shape build, release, monitoring, and app-store publication processes.
• Contribute to features from ideation through release and subsequent improvement, using AI tools such as Claude Code while maintaining output quality and correctness.

Requirements

• Freelance status and senior-level experience with TypeScript, React Native, and Expo.
• Experience taking mobile applications beyond implementation through release.
• Strong understanding of React, component architecture, state management, and asynchronous data flows.
• Knowledge of iOS and Android platform differences, performance troubleshooting, platform issues, and debugging.
• Experience integrating APIs and understanding API contracts, authentication, validation, and error handling.
• Ability to understand existing API endpoints, diagnose app-backend issues, and independently extend interfaces.
• Experience with automated testing, maintainable code, and clearly documented technical decisions.
• Independent, pragmatic working style with clear communication and customer-focused judgment.
• Fluent German and good English skills.
• PHP and Symfony knowledge is preferred; EAS, Swift or Kotlin native modules, app-store publication, mobile release processes, published apps, open-source contributions, and GitHub experiments are additional advantages.

Benefits

• Remote-first work with no location requirement.
• Flexible, trust-based working environment with substantial autonomy.
• Opportunity to contribute to company strategy and culture.
• Engaged team working on innovative solutions.
• Regular team events.