Senior Backend Expert (Java / Spring Boot) 📍 Remote | Austria-based project | 10–15 days/month 📅 Start: August 2026 | ⏳ 3–4 months | B2B For one of our clients, we are currently looking for an experienced Senior Backend Expert to support a strategic transformation project in the area of Geographic Information Systems (GIS). The initiative focuses on modernizing a legacy Oracle-based system into a cloud-native microservices architecture based on Java / Spring Boot, PostgreSQL and Kubernetes. The selected expert will act as a technical authority, working closely with internal architects and the engineering team to review, challenge, and strengthen the current solution before scaling development internationally. Your responsibilities: Review and challenge existing microservices architecture Validate service boundaries, API design, and data ownership Identify architectural risks, bottlenecks, and anti-patterns Support decoupling from Oracle-based legacy architecture (no direct JDBC access) Contribute to and review architectural documentation (Arc42, DACI) Design, review, and optimize Java/Spring Boot APIs Assess API scalability, resilience, and code quality Review event-driven integration patterns (e.g. Kafka, mapping services, GIS databases) Evaluate latency, idempotency, and system reliability Your profile: Strong experience with Java / Spring Boot microservices Proven background in software architecture design and technical reviews Experience with Oracle and/or PostgreSQL databases Knowledge of event-driven architectures (Kafka, outbox pattern) Nice to have: Experience in GIS / geospatial systems Familiarity with routing, geocoding or geospatial APIs (e.g. HERE) Experience with Kubernetes environments If you are interested in a short-term, high-impact architecture role in an international environment, we would be happy to hear from you.