Senior Java Backend Engineer– Identity & Security (REF5698K)

As Hungary’s most attractive employer in 2025 (according to Randstad’s representative survey), Deutsche Telekom IT Solutions is a subsidiary of the Deutsche Telekom Group. The company provides a wide portfolio of IT and telecommunications services with more than 5300 employees. We have hundreds of large customers, corporations in Germany and in other European countries. DT-ITS recieved the Best in Educational Cooperation award from HIPA in 2019, acknowledged as the the Most Ethical Multinational Company in 2019. The company continuously develops its four sites in Budapest, Debrecen, Pécs and Szeged and is looking for skilled IT professionals to join its team. We are looking for a highly skilled Senior Java Backend Engineer to join a team building Germany's next-generation Identity Provider platform for the national healthcare Telematics Infrastructure (TI), enabling millions of statutory health insurance members to securely access digital healthcare services. This is a security-critical, gematik-regulated platform built on Java 25 and Spring Boot 4.1 , delivering production-grade OAuth 2.0/OIDC identity services, hardware-backed cryptography, PII protection, and audit-grade quality. Our backend is designed as a domain-driven modular monolith (Modulith) that continuously evolves toward a clean hexagonal architecture. As a Senior Java Backend Engineer , you will own bounded-context modules end-to-end—from domain design and implementation to testing, operations, and architectural evolution—helping shape one of Germany's most advanced digital identity platforms. Key Responsibilities: Design, implement, and maintain backend services using Java 25 and Spring Boot 4.1 Evolve the existing modular monolith toward a cleaner hexagonal architecture, continuously improving domain separation and maintainability. Implement and secure OAuth 2.0/OIDC identity and access management flows and APIs. Develop and maintain RESTful APIs and service interfaces. Work with PostgreSQL , including schema design, optimization, and Flyway database migrations. Implement event-driven integrations using Apache Kafka. Contribute to security engineering initiatives, including: HSM-backed key management Data encryption Personal data protection Compliance with healthcare and security regulations Develop and maintain automated testing using JUnit 5 and Testcontainers. Improve observability and operational readiness through structured logging, metrics, and tracing with OpenTelemetry. Collaborate closely with Architects, SREs, Security Engineers, and QA Engineers in an agile, quality-focused environment. Participate actively in code reviews, architectural discussions, and technical documentation. 5+ years of professional experience in backend software engineering. Strong expertise in: Java Spring Boot REST API development PostgreSQL Experience implementing OAuth 2.0, OpenID Connect (OIDC), or similar authentication and authorization solutions. Experience designing and developing modular, maintainable backend systems. Understanding of modern software architecture principles and architectural evolution toward decoupled systems. Experience with: JUnit CI/CD pipelines Git-based development workflows Experience working in regulated, security-critical, or compliance-driven environments. Fluent English, both written and spoken. Advatanges: Experience with: Apache Kafka Avro Schema Registry Flyway Testcontainers Knowledge of: Spring Security OpenAPI / Swagger Micrometer OpenTelemetry Docker and Kubernetes experience. Experience with: Hardware Security Modules (HSM) Applied Cryptography Secure Software Development Practices Familiarity with: Hexagonal Architecture Domain-Driven Design (DDD) ArchUnit Experience in digital identity, healthcare, or public-sector platforms. German language skills are considered a strong advantage. Technology Stack Backend Development Java 25 Spring Boot 4.1 REST APIs Spring Security Identity & Security OAuth 2.0 OpenID Connect (OIDC) HSM-backed Key Management Data Encryption Security Compliance Database & Messaging PostgreSQL Flyway Apache Kafka Avro Schema Registry Testing & Quality JUnit 5 Testcontainers Code Reviews CI/CD Observability OpenTelemetry Micrometer Structured Logging Metrics & Tracing Architecture & DevOps Modular Monolith (Modulith) Hexagonal Architecture Domain-Driven Design (DDD) Docker Kubernetes Git What We Offer Opportunity to contribute to one of Germany’s most advanced digital identity platforms. Work in a highly modern environment using Java 25 and Spring Boot 4.1. Exposure to cutting-edge technologies in identity management, security, and healthcare platforms. Strong engineering culture with emphasis on architecture, code quality, and technical excellence. Collaboration with highly experienced architects, security specialists, and platform engineers. Professional growth opportunities in software architecture, cybersecurity, and identity solutions. International and multicultural working environment. * Please be informed that our remote working possibility is only available within Hungary due to European taxation regulation.