Senior Web & Mobile Developer

Role overview

A senior engineering role focused on building and evolving customer-facing experiences across web and mobile, alongside internal back office applications used to operate a casino platform. The position works across React.js web applications and React Native mobile apps in a regulated, high-traffic environment, collaborating closely with product, design, QA, backend engineering, and casino operations.

Responsibilities

- Build and maintain high-performance web applications in React.js and mobile applications in React Native using TypeScript - Break features into requirements, contribute to estimation, refine user stories, and define appropriate test coverage - Uphold frontend and mobile code quality and perform code reviews for other engineers - Collaborate with backend developers and architects on REST, GraphQL, and WebSocket API design and integrations - Support QA, product, and release management through safe production deployments - Implement mobile capabilities such as push notifications, background processing, and offline or local content storage - Contribute to continuous integration and delivery for web and for App Store and Google Play releases - Use analytics, debugging, and performance tooling to continuously improve the end-user experience

Requirements

- 5+ years of professional frontend or mobile application development experience in production - Strong React.js expertise and 3+ years of production React Native experience with TypeScript - Solid TypeScript, JavaScript, HTML, and CSS knowledge - Extensive experience with state management in large applications using MobX, Redux, or similar tools - Hands-on integration experience with REST, GraphQL, and WebSocket APIs - Strong understanding of the full client development lifecycle, including structure, platform and device APIs, debugging, performance, security, testing, and deployment - Based in Poland and able to work fully remote - Effective written and verbal communication in English

Nice to have

- Experience in gaming, sportsbook, fintech, or another high-traffic, regulated environment - Strong browser-based debugging and web performance testing experience - Familiarity with Webpack and modern frontend or mobile testing libraries - Production experience with MobX - Exposure to backend or full-stack development and API design - Experience mentoring engineers or taking technical ownership across web and mobile workstreams

Benefits and work setup

- Fully remote within Poland - B2B contract, full-time engagement