Senior Fullstack Mobile Engineer en Remote, Spain, España

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.

• 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 navigation structure, rendering, native integration, and alignment with mobile patterns — catching issues before release.
• Contribute to and evolve mobile engineering standards within the team — component architecture, native integration, testing, and release policy.
• Monitor the operational health of shipped work — track releases and staged rollouts, watch release health, and respond to post-release issues on both platforms.

• Broader backend and database experience.
• Experience with event-driven architectures and asynchronous messaging patterns.
• Experience operating high-traffic, low-latency systems.
• Experience with offline-first architectures and data synchronization over unreliable networks.
• Familiarity with React Native's New Architecture (JSI, Fabric, TurboModules, Codegen) and the native library compatibility constraints of migrating to it.
• Native development depth in Swift and/or Kotlin beyond React Native.
• Experience with in-person or mobile payments and fintech products.
• Experience with Stripe Terminal, Tap to Pay, or NFC.
• Experience in a distributed, remote-first engineering organization.

• The compensation range for this role is: €5,700 - €6,500 gross per month.
• Final compensation will be determined based on relevant experience, skills, qualifications, and alignment with the role's requirements.
• Private medical insurance for the employee and their family
• 23 paid vacation days per year
• 11 paid public holidays per year
• 5 company-paid sick leave days
• English learning courses
• Relevant professional education
• Gym or swimming pool
• Home Office Setup Assistance: the company offers assistance with purchasing furniture (office chair, office desk, monitor) and other items to create a comfortable workspace
• Co-working
• Remote working

EUR 79,800–91,000 per year

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.

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 https://jobeax.com/link/JSd7UYCSg572jJDY (Koa, NestJS) and MongoDB. The frontend stack includes Webpack, https://jobeax.com/link/tzGekrj9a8ToGEDv, 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.

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.

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.

Engineering

• Location: Spain, Remote
• Language: Fluent in Russian; English (B2)

• 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
• https://jobeax.com/link/JSd7UYCSg572jJDY, NestJS, React, MongoDB, ClickHouse, and Redis across the backend and web stack

• 8+ years of professional software development experience, including 3+ years with React Native.
• Proficiency in React Native and TypeScript — the primary craft.
• Strong JavaScript fundamentals — asynchronous programming, event loop behavior, error handling.
• Working knowledge of relational and document databases — data modeling, querying, indexing.
• Understanding of RESTful API design and HTTP fundamentals — able to work across https://jobeax.com/link/JSd7UYCSg572jJDY backend services, API contracts, database queries, and web frontend code.
• Familiarity with the native iOS and Android platforms and their tooling (Xcode, Android Studio, Gradle).
• Understanding of mobile OS fundamentals — app lifecycle, background execution, permissions, and memory constraints.
• Experience with automated testing practices (unit, integration, E2E).
• Understanding of mobile security — secure storage and handling of sensitive and payment data.
• Confident day-to-day use of AI-assisted development tools — for research, troubleshooting, and implementation.
• Ability to independently diagnose common React Native production issues — rendering, navigation, networking, and app lifecycle.
• Track record of owning mobile initiatives end-to-end — from requirements through store release, including the backend and web frontend changes they require.
• Experience designing mobile application architecture — trade-offs in performance, reliability, and observability across iOS and Android.
• Experience designing or integrating native modules and SDKs where React Native abstractions are insufficient — including focused Swift/Kotlin changes and debugging across the JavaScript and native layers.
• Experience owning the release process — app signing, store submission, and staged rollouts.
• Experience establishing mobile engineering practice from little — standards, CI/CD, and release — across inherited and greenfield codebases.
• Experience designing resilient asynchronous and event-driven backend interactions (messaging, queues).
• Experience with mobile production operations — monitoring, crash reporting, incident response, and rollback policy.
• Demonstrated ability to mentor and develop less experienced engineers.
• English proficiency sufficient for daily written and verbal communication.

• A strong, collaborative product team that owns what it builds
• Clear product vision and access to real customer feedback from global nonprofit leaders
• Flat structure: no politics, just great work with great people
• Transparent company culture-we share how we’re growing, where revenue comes from, and what’s next
• Long-term focus: we offer equity options and value sustained, meaningful contribution

**Please note: All official correspondence from Fundraise Up will exclusively originate from the @fundraiseup.com domain. Exercise caution and ensure the authenticity of emails claiming to be from our company. 

We are an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. We do not discriminate on the basis of race, color, religion, gender, sexual orientation, gender identity or expression, age, national origin, disability, or any other characteristic protected by applicable law in the countries where we operate.