Commerce Media Tech, part of Team Internet Group, is a dynamic ad-tech company based in Kraków. We’re passionate about building cutting-edge software that powers smarter, more effective online advertising. Our diverse team of software engineers, UX designers, product managers, marketers, and other talented professionals work together to deliver innovative advertising solutions for brands, agencies, and digital marketers worldwide.We're the team behind Zeropark, a trusted performance marketing platform. Now, we're building something new from the ground up — a next-generation Commerce and Retail Media platform.What you'll be working on: A greenfield project with the chance to shape its technical direction Scalable, lightweight architecture for publishers, advertisers, and retailers AI-driven real-time shopping intent matching based on page context Cleanroom data integrations for precise attribution and targeting Natural language campaign management via our MCP (Model Context Protocol) and AI agents Innovative ad formats tailored for commerce and retail media Key outcomes of the roleOur Team Culture:We're a tight-knit, motivated group that works end-to-end — from planning and building to deploying and maintaining. We collaborate closely with the business team and have full access to production environments, with no external ops or support layers.Our stack Kotlin, Java 24/25 Frameworks: Spring, Spring Boot, Spring Data, Spring Cloud Communication: Kafka (MSK), REST AWS: ECS, Fargate, Lambda, ECR, CodeDeploy, Cognito, Route53 and more Storage: ClickHouse, Aurora, DynamoDB, Elasticache, MemoryDB, Redshift, S3 Frontend: Typescript, Angular, Vue, Nx Tools: Terraform, Gradle, Docker, GitHub Actions Monitoring: DataDog, PagerDuty Key responsibilities Build new features using AWS services at scale Design architecture with focus on scalability and maintainability Work closely with Product and Business teams On-call rotation(paid, once per 8 weeks after onboarding) About you 5+ years of backend engineering experience (JVM ecosystem) Bring demonstrable experience in building distributed systems Know your way  around testing (unit, integration) Comfortable diving into frontend work when necessary  Own your work end-to-end from design decisions to production AWS or other major cloud provider experience  Daily use of AI coding tools (eg Claude Code, Copilot, Cursor) with critical thinking Be able to communicate clearly and work independently  Fluent in Polish and English Experience and skills that will help you succeed Kotlin experience (or willingness to learn - it's our primary language) Kafka or similar event streaming platforms Big Data processing using Apache Spark