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 , includ