(Senior) Full Stack Next.js Developer (f/m/d)

ZEAL Network SE is a dynamic, international group of companies that has been creating exciting and innovative lottery experiences for over 20 years. As Germany’s largest provider of online lotteries through our brands LOTTO24 and Tipp24, and a trusted partner of Spain’s ONCE, the second-largest national lottery, we’re shaping the future of the lottery industry. We are passionate about driving innovation, as demonstrated by our newest brands, Freiheit+ and Traumhausverlosung, which bring fresh and exciting dreams to life. Additionally, through ZEAL Ventures, we invest in inspiring e-commerce start-ups like Omaze and DAYMADE, fueling fresh ideas and opportunities. We are looking for a (Senior) Full Stack Next.js Developer (f/m/d) to join our team and contribute to building scalable workflows, integrating backend services and defining reusable frontend patterns for a platform used by internal colleagues across multiple markets and business domains. With direct access to users, you will help shape practical solutions together with Product and UX. Your tasks: Shape and build a modern Next.js application from scratch, creating the technical foundation for a scalable internal platform Take ownership of frontend topics and drive technical decisions Work closely with product, design and backend teams in a lean, agile environment Integrate and evolve RESTful APIs in collaboration with backend engineers Ensure high-quality implementation of UI/UX designs with a strong focus on performance and scalability Write and maintain tests to ensure reliability, security and performance Contribute to deployment, monitoring and overall application stability together with DevOps Identify and drive improvements in performance, user experience and conversion Measure, analyze and iterate on product features based on data What you offer us: Strong experience as a Senior Full Stack or Frontend Engineer with a focus on modern web technologies Deep expertise in JavaScript, React and Next.js (App Router, Server Components, Server Functions) Proficiency in TypeScript, HTML5 and CSS3 Hands-on experience with tools such as Tailwind CSS, React Hook Form, TanStack Query, Zod, Shadcn/UI or similar (Tailwind CSS is a must have, everything else nice to have) Ability to write clean, maintainable and performant code and design scalable architectures Solid experience integrating and working with REST APIs Experience with testing strategies for frontend applications (nice to have) Interest in using modern development tools, including AI-assisted workflows, to improve productivity and quality (nice to have) What We Offer State-of-the-art technologies and an agile environment (Check our Tech Radar: https://lotto24.github.io/tech-radar/ ) A modern, dynamic culture grounded in the success of a leading-edge e-commerce company. A talented team of ambitious, like-minded colleagues where your knowledge and ideas truly make an impact. Ongoing personal growth, supported by an annual development budg