Full-Stack Engineer - AI Platform (m/f/d)

Salary range: 22,000 - 26,000 PLN net + VAT B2B Your position in our team Backend (Java) Build and maintain Java services powering our AI platform, APIs, data pipelines, and ERP integrations Develop LLM orchestration, context management, and conversation state handling for our Nexus agent Implement authentication, rate limiting, cost optimization, and observability tooling Frontend (React / TypeScript) Build chat widgets, dashboards, and self-service tools for the AI agent Integrate AI features into Magicline interfaces for a seamless user experience Enable analytics, workflow builders, audience segmentation, and campaign tools Your profile 5+ years building production web apps with strong backend (Java/Spring Boot) and frontend (React/TypeScript) skills Experience with real-time interfaces (WebSockets, SSE, polling) and modern state management (MobX, Redux) Comfortable with web fundamentals: HTTP, REST APIs, responsive design, and component libraries (MUI or similar) Skilled at writing automated tests and maintaining high code quality Strong collaboration skills; you thrive in cross-functional teams Fluent English (C1); German is a plus Nice to have Exposure to AI/ML products, chat interfaces, or data visualization libraries (D3, Recharts) Knowledge of accessibility standards (WCAG), internationalization, B2B SaaS, ERP, or CRM Understanding of prompt engineering, agent frameworks, or AI observability Your Benefits with us Benefits package – private medical care and a sports card to support your health and well-being Flexible working hours – manage your schedule and enjoy a real work-life balance Flexible work model – work fully remotely or combine it with on-site collaboration at our modern office in Warsaw Flexible employment options – choose the type of contract that best suits your needs Access to Udemy Business – grow your skills with thousands of high-quality online courses Unique experience in the Fitness and SaaS industry – join a market-leading company in a dynamic, fast-growing field International team – collaborate with talented colleagues from around the world in a diverse and inclusive environment Unforgettable company events – take part in engaging team-building activities and memorable celebrations No dress code – express your personal style and feel comfortable at work Our job advertisements are open to all applicants regardless of gender, age, nationality, religion, social background, disability or sexual orientation. The Sport Alliance stands for diversity and, as a member of the Diversity Charter, is committed to a prejudice-free, open and progressive working environment. Your Job at  Sport Alliance Headquartered in Hamburg, Sport Alliance is one of the leading software companies in the fitness industry, specializing in providing software solutions for efficient studio management, financial services, and mobile applications. The company serves over 10,000 gyms, including 14 out of Europe’s top 30 chains and 130 international chains in 55 countries – like FitX, Fitness First (LifeFit Group), McFIT (RSG Group), clever fit, and Bodystreet. The product portfolio contains Magicline, one of Europe’s leading membership management ERP solutions for the fitness market, assisting fitness studio operators in optimizing and digitizing their facilities. Complementing Magicline is PerfectGym with its gym software focusing on international chains and franchises. Part of the company is also MySports, the member platform tailored to enhance the gym experience for members. Additionally, Sport Alliance’s portfolio includes Finion, a financial services provider dedicated to supporting studios in efficiently managing membership fees, from billing to debt collection. More information about the company is available on our website. You haven't found the right position for you yet? Here you can find more job offers! SPORT ALLIANCE Learn more SABRINA GROSS HR Generalist For me, the special thing about Sport Alliance is the corporate culture: professional work on equal terms with a lot of personal responsibility in a family atmosphere, coupled with a shared passion for our vision. I am happy to face new challenges every day and to grow with them. PHILIPP RUSCH Chief Financial Officer Our strong growth and ongoing internationalisation brings interesting challenges to the Finance organization. At the same time it makes work fun and provides excellent development opportunities for our finance professionals.