Senior Java Engineer (Krakow)

🎰 Senior Java Engineer: Build the Wallet Behind Millions of Players Adaptiq × a major online gaming operator The challenge: Picture a platform where millions of players hit "play" at the same moment, every action moves real money, and the answer must come back in under a second. Now picture building it from scratch . That's the PAM (Player Account Management) platform: real-time financial transactions, strict regulation, zero tolerance for lost cents, and traffic spikes that would make most systems sweat. No legacy code to inherit. Just a blank page and hard problems. Your role: You'll design and build the core backend of the platform and own your features end-to-end : from RFC to production monitoring. You'll work side by side with Principal Engineers, with real autonomy and real influence on the architecture. What you'll do: Build services in Java 17+ / Spring Boot for wallets, ledger, payments, bonuses, and account state Create REST APIs and Kafka -based event flows for frontends, ops tools, and partners Make correctness non-negotiable: idempotency, clear transaction boundaries, failure handling, solid testing Bake in compliance: KYC/AML , responsible gaming, audit trails Keep production healthy with metrics, tracing, alerts, and on-call Shape the platform through RFCs and code reviews, and mentor teammates Work with AI-assisted tools daily Help migrate live from the existing third-party platform (parity testing, data validation, cutover) What you bring: 5+ years in backend engineering, with strong Java 17+ and Spring Boot Experience with high-integrity transactional systems: payments, wallets, billing, banking, e-commerce, or gaming Deep PostgreSQL (or similar) knowledge: schema design, ACID, locking, tuning Event-driven architecture experience (Kafka, RabbitMQ), including idempotency and retries Automated testing as a habit: unit, integration, contract Hands-on production experience with containers, CI/CD, observability, and incident troubleshooting Solid grasp of multi-threading and fault-tolerant design Good English and comfort working across time zones Bonus points: ✦ iGaming, betting, or fintech background ✦ Kubernetes and AWS (VPC, IAM, EKS, auto-scaling) ✦ Compliance-driven development experience ✦ Agentic development workflows If you want your code to handle real money, real scale, and real responsibility, let's talk.