Freelancer Senior Mobile Engineer (React Native, Expo, TypeScript) m/f/d

Welcome to easybill.

Over 22,000 companies rely on easybill. We ensure that invoices, processes, and integrations run smoothly in everyday business. With easybill-mobile, we are bringing central functions of our platform to iOS and Android – and we are looking for you to help shape the app technically and from a product perspective.

You will receive clear priorities, short paths, and room to solve things cleanly. With us, you will take responsibility: for technical decisions, well-thought-out user guidance, and an app that our customers can rely on on the go.

The ideal profile? You are a freelancer, deeply proficient in TypeScript, React Native, and Expo, understand the specifics of mobile applications, and want to significantly shape a product in its early development phase. Ideally, you also have knowledge of PHP and Symfony to help shape functions on the REST API side.

Tasks

You will further develop easybill-mobile based on React Native, Expo, and TypeScript for iOS and Android. A technical foundation with login, dashboard, and document overviews is already in place. You will build upon this and shape the next steps together with the team.

• You will translate requirements related to invoices and documents into understandable mobile workflows and high-quality native interfaces.
• You will further develop the app architecture and create maintainable structures for navigation, reusable components, forms, and data access.
• You will connect our REST API and ensure reliable data management: from typed interfaces and validation to caching, loading states, and error handling.
• You will work at the interface between the app and the backend. If necessary, you will extend our REST API based on PHP and Symfony so that new mobile functions can be implemented end-to-end.
• You will work on secure authentication, session management, and the careful handling of sensitive customer and business data.
• You will keep an eye on performance and platform specifics – even with changing network connections, app switching, and different devices. Accessibility and multilingualism are part of your product quality.
• You will secure changes with automated tests and check behavior on simulators and real devices. You will help shape build, release, and monitoring processes up to the publication in the app stores.
• You will question requirements, contribute your own solution proposals, and accompany functions from idea to publication and further development.
• You will extensively use AI tools like Claude Code in your daily development work and take responsibility for the quality, clarity, and correctness of the results.

Our mobile stack includes React Native, Expo, Expo Router, and TypeScript. In addition, TanStack Query and TanStack Form, Zod, and NativeWind. For tests, we rely on Jest and React Native Testing Library. Our existing platform and REST API are based on PHP and Symfony.

Qualifications

• You don't need to know every library already. The crucial thing is that you understand your stack, make good technical decisions, and independently learn new topics.
• You have solid experience with TypeScript, React Native, and Expo at a senior level and have accompanied mobile applications beyond pure implementation up to release.
• You understand React, component architecture, state management, and asynchronous data flows and can structure complex relationships understandably.
• You know the specifics of iOS and Android and systematically approach performance problems, platform errors, and debugging.
• You are confident in connecting REST APIs and understand API contracts, authentication, validation, and error handling.
• Ideally, you also have knowledge of PHP and Symfony. You can understand existing API endpoints, analyze errors between the app and backend, and independently extend interfaces.
• Automated tests, traceable technical decisions, and maintainable code are part of your daily development routine.
• You work independently and pragmatically, communicate clearly, and keep the benefit for our customers in mind.
• You speak fluent German and have good English skills.

Additional plus points include experience with EAS, native modules in Swift or Kotlin, as well as app store releases and mobile release processes. Your own published apps, open-source contributions, or public experiments on GitHub are also welcome.

If you don't tick every box but are an exceptionally strong engineer: Apply anyway and show us what you've built. Show us what you've built!

Benefits

• Remote-First Team – no ties to a location
• An inspiring and flexible work environment based on trust and personal responsibility
• The opportunity to contribute to shaping company strategy and culture
• A dedicated team and the chance to work together on innovative solutions
• Regular team events

Do you want to help shape easybill on iOS and Android? Then we look forward to receiving your application. We are particularly interested in projects where you have taken on technical responsibility: What did you build, what decisions did you make, and what did you learn from it?

We look forward to hearing from you!