Senior React Native Developer

Join one of Europe's largest mobile platforms, delivering digital services used by millions of users across multiple countries in Europe and North America. Built on a multi-module architecture, the platform enables rapid product development, high code reusability, and continuous expansion into new business areas. As a Senior React Native Developer, you will play a key role in shaping the architecture of a big mobile ecosystem, driving technical decisions, mentoring other engineers, and delivering high-quality solutions at scale. Your tasks Design, develop, and maintain complex mobile applications using React Native and TypeScriptDrive architectural decisions and contribute to the evolution of our multi-module platformLead technical discussions and participate in solution designReview code, mentor team members, and promote engineering best practicesCollaborate closely with Product Owners, UX Designers, Backend Engineers, QA Engineers, and ArchitectsImprove application performance, reliability, scalability, and maintainabilityContribute to CI/CD processes and development toolingSupport the integration of native mobile capabilities and third-party servicesIdentify technical debt and proactively drive improvements across the codebase Requirements At least 5 years of commercial software development experience, including at least 4 years with React NativeProven track record of building and maintaining large-scale mobile applicationsStrong expertise in TypeScript, modern JavaScript, and React HooksSolid understanding of modular and multi-module application architectureHands-on experience with MobX and React Query (TanStack Query)Knowledge of native mobile development concepts and creating native modules for iOS and AndroidPractical experience with REST APIs, GraphQL, and form management solutionsEnglish and Polish proficiency at B2 level or higherResiding in Poland required Nice to have Payment integrations and mobile wallet solutionsGeolocation and location-based servicesFirebase services and analyticsMobile security best practicesObservability and monitoring toolsBackground in large-scale international productsAgile delivery experience (Scrum/Kanban) Job no. JOB-BLY3A Sii ensures that all hiring decisions are made solely on the basis of qualifications and competence. We are committed to equal and fair treatment of all, regardless of legally protected characteristics. At Sii, we promote a diverse and inclusive work environment, in full compliance with applicable anti-discrimination laws. Benefits For You Great Place to WorkSolid financial situationContracts with the biggest brandsCentre of internal trainingsMany experts you can learn fromOpen and accessible management teamProfit sharingPassion Sponsorship programRegular integration events and tripsComfortable and well-equipped officesMySii appMedical care