Senior Fullstack Mobile Engineer

Highlights: Location: Poland, Remote Language: Fluent in Russian; English (B2) About Fundraise Up We’re Fundraise Up - a global fundraising platform built to make donating to nonprofits fast, seamless, and accessible to all. Every month, our technology powers tens of millions of dollars in donations across the globe. We focus on innovation that directly impacts results: faster load times, higher conversion rates, global payment support, and accessibility-first design. Our platform is trusted by many of the world’s leading nonprofits, including UNICEF, the Alzheimer’s Association, and a wide range of global NGOs. With a 4.9/5 rating across top software review platforms, we’re recognized not just for our impact - but for the quality of the product we deliver. A Truly Global Product We operate in the enterprise segment, serving nonprofit organizations across North America, the United Kingdom, Australia, and Europe. We’re building a large and complex product ecosystem that serves nonprofits, donors, and partners around the world. The platform includes a modern checkout experience and customizable widgets (each a standalone SPA), donor, organization, and partner portals , admin tools , and several internal apps. Our backend is powered by Node.js (Koa, NestJS) and MongoDB . The frontend stack includes Webpack, Vue.js, and React , with nearly all code written in TypeScript . For high-throughput messaging and background processing, we use Kafka (for millions of events) and Bull (Redis) . Analytics data is stored in ClickHouse , and we use Elasticsearch for search. The Team We are a distributed team of 160+ product professionals, including 80+ engineers. Our team members are mainly based across Spain, Poland, Portugal, Georgia, Armenia, Serbia, Turkey, and Cyprus. Despite our scale, we operate like a focused team — where every task matters and every voice is heard. We value thoughtful collaboration, strong engineering practices, and a product mindset. About the Mobile Team You'll join the mobile team inside our Engineering department. The team builds the products that let nonprofits accept donations in the physical world. Tap to Donate lets a staff member or volunteer accept contactless payments directly on a smartphone. Giving Station is a self-service donation point: a donor selects an amount on a tablet and pays through a connected external payment terminal. Our mobile stack: bare React Native (0.79, Old Architecture) React 19, TypeScript React Navigation 7, TanStack Query 5, React Context react-hook-form, Zod an internal UI Kit built with twrnc Stripe Terminal, Tap to Pay, external payment terminals Sentry, PostHog Node.js, NestJS, React, MongoDB, ClickHouse, and Redis across the backend and web stack About the Role You will design, build, and maintain the mobile applications that power Fundraise Up's product on iOS and Android. Mobile is the primary focus, with contributions extending to the backend and web frontend the product depends on to deliver features end-to-end. You'll work across the full development lifecycle — from requirements analysis through implementation, testing, store release, and production support — and ensure the applications are reliable, performant, and secure across the devices and OS versions in use. What You'll Do Implement features, fix bugs, and resolve production incidents across iOS and Android, extending to the backend and web frontend the product depends on — delivering tested, production-ready output that meets the team's quality bar. Own mobile initiatives end-to-end — gather requirements, design the approach, decompose into tasks, implement, and deliver to production across iOS and Android, including the backend and web frontend changes they require. Act as the team's primary technical escalation point for complex mobile problems — diagnose root causes across the app, native layers, networking, and platform behavior, and prevent recurrence. Review code and designs for correctness — component and…