SENIOR MOBILE ENGINEER (FOUNDING TEAM)

ABOUT ZAHLN Zahln, by Zysygy, is building Germany's zero-fee payment network. Merchants pay zero transaction fees. We route payments directly over SEPA Instant, bypassing Visa, Mastercard, and the entire card network chain. No hardware. No card reader. Just a phone. Nearly every digital payment in Germany today moves over infrastructure owned outside Europe, and a share of each one leaves the continent as fees. We are building the alternative on European rails: a fully software-based merchant POS and a consumer super-app for everyday financial life, payments, transport, utilities and government services in one place, settling account to account over SEPA Instant, with European data residency by design. Think what UPI did for India. We are doing it for Germany, on infrastructure Europe controls. We start on campus. Students pay in the mensa, at city merchants, and for university services from one wallet, and the institution pays no transaction fee. Everything they touch to do that is an app on a phone. This role owns it. EXIST FUNDING This role is open to students and recent graduates (within the last 5 years) of German universities who are eligible for EXIST Gründerstipendium funding. LOCATION Remote within Germany, with regular time in Augsburg. English is our working language. German is useful and not required. ROLE OVERVIEW You own the app. iOS and Android, one codebase, from an empty repository. Nobody hands you a specification and nobody reviews your architecture before you commit to it. Students will never read our deck or look at our architecture. They open the app in a mensa queue with eleven people behind them and either pay in three seconds or they do not. That moment is the whole company and it belongs to this seat. One constraint shapes everything else here: you cannot hotfix a phone. A bad build sits in review for days, and a share of your users will never update at all. So the app has to be built on the assumption that you will sometimes be wrong. Kill switches, feature flags, staged rollout, forced update, configuration driven from the server rather than baked into a binary. You decide how that works in your first weeks and it stays decided for years. There is a second frontend seat, based in India, covering web. That person also works inside the app. You set the mobile architecture and the standards, they build to them, and you review each other. The division is not permanent and we expect both of you to cross it. WHAT YOU WILL DO The consumer app, first priority - Onboarding and KYC, PIN and biometric setup, device binding, session handling. - Wallet and balance, top-up, withdrawal, transaction history, search, transaction detail, dispute reporting. - Notifications and security alerts, GDPR data export, account deletion. - Identity as it appears on a phone: document capture, liveness, eID over NFC where we use it, and the handover to and from a partner's identification flow. The hard part is not the capture. It is what a user sees when their onboarding is stuck inside someone else's system. The payment moment - QR scan, NFC tap, merchant and amount confirmation, biometric authorisation, receipt. Measured in milliseconds and optimised above everything else in the product. - Strong customer authentication in practice: which actions require re-authentication, what happens when biometrics fail, how a session survives an app switch without becoming a hole. - Campus wifi will drop a request after the money has already moved. How the app behaves in that second is a design decision, and it is yours. Merchant acceptance - What sits on the till: dynamic QR with amount, live confirmation, refund from the device. A screen, not a dashboard. Release, reliability and security - Store submission and review for both platforms, signing, versioning, staged rollout, rollback, forced update. - Crash and performance monitoring, real user metrics, and product instrumentation good enough to tell us where people abandon onboarding without shipping personal data out of Europe. - Certificate pinning, keychain and keystore, integrity checks, screenshot handling on sensitive screens, logging that never puts a token or a balance in a crash report. - Automated testing that runs on real devices, and a regression pass before every release. - Accessibility built in from the first screen rather than retrofitted. Consumer payment services in Germany carry legal accessibility obligations and our institutional clients are public bodies with their own. Later, as we grow - P2P, split bills, scheduled and recurring payments, contact handles. - The digital student ID and university services in one authenticated session: semester fee, mensa top-up, library, exam registration. - The full merchant app, with KYB, staff shifts and catalogue. - Transport, telecoms and utilities inside the wallet. None of that is pilot scope. All of it is why the decisions you make in month one matter. OUR STACK React Native with Expo, TypeScript and NativeWind on mobile. React, TypeScript and Tailwind on web, sharing design tokens, API types and validation with the app through a TypeScript monorepo. Go, Node.js, Python and PostgreSQL behind it, REST over SEPA Instant rails. Sentry for errors and performance, Maestro for device-level end-to-end tests. We chose React Native so that two engineers can work in one codebase and cover for each other. You will have real influence over everything above, and we would rather you argued with it than inherited it quietly. WHO YOU ARE - Eligible for EXIST Gründerstipendium funding: enrolled at a German university, or a graduate of one within the last 5 years. - Around three to five years building production software, with genuine depth in React Native. Not React with some exposure to mobile. You have shipped to both stores, handled a rejection, and lived with what you released afterwards. - You think in states rather than screens. Pending, failed, expired, insufficient balance, refunded, disputed. Asked to describe a payment screen, you describe all of them. - You have worked on unreliable networks and know why an automatic retry on a payment request is dangerous. - You are comfortable at the device layer: NFC and its platform limits, biometrics, camera and QR, push reliability, deep links, background states, secure storage. You know when dropping below the React Native layer is the right call and when it is showing off. - You measure performance instead of asserting it. Cold start, frame rate, time to confirmation. - You have taste and you defend it. You will push back on a design, or on a founder, when the product would be worse. - You use AI tooling seriously in your workflow and you know where it produces confident nonsense. - Comfortable with ambiguity and early-stage risk. There is no playbook yet. You will help write it. STRONG BONUS (NOT REQUIRED) - You have worked on a fintech, banking or payments app, or anything else where a bug costs someone money rather than time. - You have shipped NFC on iOS or Android and know exactly what Apple permits a third party to do. - You have built or maintained a design system inside an app. - You have run a release train under pressure: versioning, phased rollout, rollback, an emergency fix on a Friday. - You have made an app genuinely accessible and know what a screen reader does to a layout you thought was fine. - You design as well as build, in Figma or directly in code. BENEFITS - Be part of a founding team eligible for EXIST Gründerstipendium, a grant from the German government that funds you to build. - You own the consumer surface of the company. Not a feature team, not a queue of tickets, not someone else's architecture. - Thousands of students on the first campus, using what you built, telling you about it the same day. Feedback in weeks rather than quarters. - This is European payment infrastructure rather than a skin on somebody else's. The rails, the data and the supervision stay in Europe, and the app is where that turns into something a person can hold. - Flexible hours and remote within Germany, with regular time in Augsburg. We expect you in the mensa at 12:15 sometimes, watching people use it. - Early stage means something here. Small team, real ownership, no queue of forty pull requests ahead of yours. - You will work with people who left stable paths to build a faster, simpler way to move money in Germany. Less bureaucracy, more momentum. - For the right person who grows with the company, equity is a conversation we will have when the time is right. Connect with the Founder www.linkedin.com/in/shabbir-maimoon