Senior Java Backend Engineer– Identity & Security (REF5698K)

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.