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SENIOR FRONTEND ENGINEER, REACT AND REACT NATIVE (FOUNDING TEAM)

Zahln

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Questions you are likely to be asked

  1. Why do you want to join Zahln?
  2. What is your experience with React Native? Tell me one thing you learned the hard way.
  3. What changes when an app grows from a thousand users to a million?
  4. How do you keep an app smooth on low-end phones?
  5. Tell me about an app release that went wrong. What happened next?

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**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. If you spent the UPI years building payments in India, you already know how the next five years play out here. The difference is that you would be arriving at the beginning of it. **ROLE OVERVIEW** You own everything that runs in a browser, and you build in the app alongside our mobile engineer. That combination is deliberate. For the first months the app is the company, so most of your time goes into React Native: the merchant acceptance surface, and consumer features built inside the architecture our mobile engineer sets. In parallel you build the internal operations console, which decides whether we can actually run a payment network rather than only launch one. As merchants and institutions arrive, you move into owning the full web surface. Between the two of you, that is every interface Zahln has. There is nobody else, and there will not be for a while. That is the offer and the risk, stated plainly. The internal tooling is the part most engineers skip past when they read an advertisement like this. Do not. When a student is standing at a counter with a payment stuck between two systems, somebody in our team has ninety seconds to work out what happened and fix it. Whether they can is entirely a question of what you built for them. **WHAT YOU WILL DO** * In the app, with our mobile engineer - Merchant acceptance on the till: dynamic QR with amount, live confirmation, refund from the device. - Consumer app features alongside the app owner, inside their architecture and their release train. * Internal operations tooling - Find a user, a merchant or a transaction in seconds, from a partial name or a wrong amount or a time of day. - Issue a refund, freeze an account, resolve a stuck payment, and leave a record that explains why. - Work the queues: KYC and KYB exceptions, sanctions screening hits, merchant onboarding review, reconciliation mismatches. - Permission-aware throughout. What a support agent sees is not what an administrator sees, personal data stays masked until there is a reason to reveal it, and the reveal is logged. * Institutional reporting - What a university finance department actually asks for, which at this stage is a reliable scheduled export rather than a reporting product. - Settlement and reconciliation views as volume grows. * Design system on web - Implement it once, alongside our designer, sharing tokens with the app so the two read as one company instead of two interpretations of the same Figma file. - German and English throughout, including the formal register institutions expect, and layouts that survive German compound nouns. - Accessibility in the dense tables and dialogs where it is hardest, because that is where our obligations actually land. * Later, as we grow - The full merchant and manager dashboard: live transaction feed, history at scale with fast filtering across tens of thousands of rows, partial and full refunds, staff and role management with per-staff limits, product catalogue, disputes. - German fiscalisation and accounting surfaces as we move beyond campus: DATEV export, Kassenbuch, VAT treatment. - Price groups for student, staff and guest pricing, per-institution theming, adoption analytics for universities and Studierendenwerke. That is the roadmap rather than the first six months, and it is yours when it arrives. **OUR STACK** React, TypeScript and Tailwind on web. React Native with Expo and NativeWind on mobile, one codebase for iOS and Android. A TypeScript monorepo so that web and app share design tokens, API types and validation instead of drifting apart. Go, Node.js, Python and PostgreSQL behind it, REST over SEPA Instant rails. Sentry, Playwright on web, Maestro on device. **WHO YOU ARE** - Three to five years or more building production web applications in React and TypeScript, with real React Native experience next to it. The mobile half is not optional and it is where you start. - You have built dense, data-heavy interfaces that stayed fast. Virtualised or paginated tables, complex filtering, exports. You know why naive rendering falls over, because you have watched it happen. - You have worked with real-time data, and with what happens when the connection drops and comes back holding stale state. - You understand that a financial interface is different. A stale balance, a double-submitted refund or an ambiguous status is a money incident rather than a UI bug. Confirmation, idempotency and unambiguous state are instincts for you, not requirements somebody had to give you. - You have built tools for internal users as well as customers, and you know how differently the two should be designed. - You own what you ship through deployment and monitoring, and you go and look at it afterwards. - You can explain a technical decision to somebody non-technical. At this size that matters more than it will later. - 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 built a merchant, admin or back-office console for a payments company, a marketplace or a fintech. Time at or around India's payments companies is directly relevant. - You have worked on reconciliation, settlement or dispute tooling, where correctness is the entire job. - You have built or maintained a design system used across more than one surface. - Accessibility and internationalisation in practice rather than in principle. - Frontend security in a regulated context: session and token handling, CSP, personal data on screen and in logs. - Enough backend comfort to fix a small API yourself rather than wait for someone. **WHAT YOU GET** - Founding engineer scope. The entire web surface of the company, plus real work in the app. - Users within months. Merchants and institutions use these tools daily from launch and you hear about it immediately when something is wrong. - Hard problems that are not artificially hard: real-time financial data, large datasets, interfaces where being wrong costs money. - Direct work with the founders, and a genuine say in a stack you will live inside for years. - A small team across two countries, real ownership, and 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 Europe. **Connect with the Founder** www.linkedin.com/in/shabbir-maimoon

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Listed on wellfound · posted 2026-09-20. ApplySarthi collects openings and links to application pages; the role is advertised by Zahln, not by us.