Senior Java Developer (Security Platform)

Are you passionate about building secure, high-performance platforms? We are looking for a Senior Java Developer to join our team and work on a cutting-edge security platform. This is a remote role open to candidates across Europe and Ukraine. At Sigma Software, we create innovative solutions for complex ecosystems, ensuring security, scalability, and compliance at every step. You will be part of a talented engineering group designing the unified access layer for distributed services. Why join us? You will work on a mission-critical project with advanced security architecture, collaborate with skilled professionals, and contribute to a platform that supports global-scale operations. CUSTOMER Our customer is a leading EdTech company that uses AI and data-driven technologies to personalize learning experiences, optimize user engagement, and improve marketing effectiveness through advanced audience targeting and analytics. PROJECT The project focuses on developing a centralized platform access layer that combines API gateway capabilities, service orchestration, data composition, and fine-grained authorization mechanisms. The platform provides a secure foundation for governance across the ecosystem, supporting complex organizational hierarchies, regional compliance requirements, and consistent policy enforcement. Design and evolve the platform access architecture for a large-scale distributed ecosystem Build and maintain a unified API layer over multiple distributed services Implement fine-grained ABAC authorization at scale, supporting complex hierarchies and relationships Develop fail-closed security architectures with strict enforcement guarantees Manage regional compliance, data residency, and routing requirements Ensure consistent data visibility rules across all products and services Design high-performance authorization evaluation systems and policy engines Maintain auditability, traceability, and security transparency mechanisms Collaborate with platform and product teams on API and access design Contribute to architectural decisions and security standards At least 5 years of commercial software engineering experience Strong expertise in Java development Strong proficiency in Java 21+ and modern Java features, including virtual threads, NIO, and concurrent programming Hands-on experience building high-performance backend systems with a strong focus on scalability and low latency Experience working with GraalVM Native Image and optimizing Java applications for native execution Solid understanding of HTTP protocol internals, connection management, streaming, and API performance optimization Experience processing large volumes of JSON using streaming APIs and memory-efficient techniques Strong knowledge of performance tuning, profiling, benchmarking, and JVM optimization Experience designing and implementing caching strategies and cache invalidation mechanisms Solid understanding of authentication, authorization, and security best practices in distributed systems Experience building or maintaining API gateways, proxies, load balancers, service mesh components, or other infrastructure-level services Strong understanding of event-driven architectures and distributed systems design Experience writing comprehensive automated tests for performance-critical and protocol-level components Upper-Intermediate or higher English proficiency WILL BE A PLUS Experience with Netty and high-performance networking applications Experience with service mesh technologies such as Istio, Envoy, or Dapr Hands-on experience with authorization frameworks such as OPA, Cedar, Zanzibar, or Oso Experience with Google Cloud Platform, including Pub/Sub, BigQuery, Memorystore, or Redis Experience deploying and operating applications on Kubernetes Familiarity with gRPC, Protocol Buffers, and HTTP/2 Experience working in regulated domains such as Healthcare, Education, or FinTech Knowledge of jlink, AppCDS, CRaC, or other JVM optimization technologies PERSONAL PROFILE Proactive and detail-oriented Thrives in collaborative environments Enjoys solving complex integration challenges Comfortable experimenting with new technologies Committed to improving data systems