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.

JOB DESCRIPTION
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

QUALIFICATION

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