At least 5 years of commercial experience as a Java Developer in complex backend systems, Hands-on experience with Kafka, Redis, and AWS in production-grade environments, Solid understanding of distributed, high-throughput, and event-driven architectures, Experience with multi-threaded applications, RESTful services, and scalable backend design, Good command of English (B2/C1), enabling effective collaboration in an international team, Residing in Poland required, Experience working with or integrating AI / Machine Learning systems