Senior Java Engineer - AI Platform

Do you want to make a change in the FitTech industry with an agile, fast-moving team? How about being part of the culture that truly values your opinions and ideas? If you want to develop software that really matters and deliver the best solutions for our clients alongside a like-minded team, then you're in the right place. Be part of the digital transformation of the fitness industry!We are looking for a Senior Backend Engineer to join our AI speedboat team at Sport Alliance. You’ll be the technical backbone of our AI platform, designing and building Java services for multi-agent conversational AI, predictive analytics, and member engagement. This hands-on role lets you own the architecture and implementation of production AI systems in a small, fast-moving team.Your position in our teamLead the design and development of core Java services powering our multi-agent AI platform.Architect integrations with Magicline ERP for memberships, bookings, and payments.Build LLM orchestration infrastructure, managing prompts, model routing, and fallback strategies.Implement authentication, authorization, and multi-tenancy for enterprise clients.Develop data pipelines and feature stores to feed predictive ML models.Create robust APIs, monitoring, and automated testing for AI systems.Contribute to key technical decisions around model selection, deployment, and scaling.Your profile5+ years in backend (Java) or full-stack engineering.Strong system design: microservices vs monoliths, synchronous vs asynchronous patterns.Hands-on with Java frameworks (Spring Boot), API design, and database modeling.Familiarity with AI/ML infrastructure or building integrations with ML models.Experienced in multi-tenant SaaS, CI/CD, monitoring, and production operations.Collaborative mindset: code reviews, mentoring, and technical discussions.Fluent English (C1); German is a plus.Nice to have:Full-stack: React + TypeScriptExperience with prompt engineering, agent frameworks, or LLM-powered appsBackground in B2B SaaS, ERP, CRM, or complex operational platformsEvent-driven architectures, Kafka, RabbitMQGDPR & EU AI Act knowledgeExperience in fitness, health, or membership-based businessesYour benefits with usBenefits package – private medical care and a sports card to support your health and well-beingFlexible working hours – manage your schedule and enjoy a real work-life balanceFlexible work model – work fully remotely or combine it with on-site collaboration at our modern office in WarsawFlexible employment options – choose the type of contract that best suits your needsAccess to Udemy Business – grow your skills with thousands of high-quality online coursesUnique experience in the Fitness and SaaS industry – join a market-leading company in a dynamic, fast-growing fieldInternational team – collaborate with talented colleagues from around the world in a diverse and inclusive environmentUnforgettable company events – take part in engaging team-building activities and memorable celebrationsNo dress code – express your personal style and feel comfortable at work