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Halian

BACK-END DEVELOPER (m/f/d)

On site

Brussels, Belgium

Senior

Freelance

18-01-2026

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Skills

Java Kotlin Jira MongoDB PostgreSQL Encryption CI/CD Docker Kubernetes Security Testing Architecture Databases Organization Confluence Agile Spring Hibernate Spring Boot Maven Microservices

Job Specifications

A leading public-sector organization driving large‑scale digital health and data‑exchange initiatives across Europe. The institution is seeking a Senior Back‑End Developer to support the development of secure, scalable platforms enabling cross‑border digital services.

Responsibilities:

Develop and maintain back‑end applications using modern frameworks and technologies, ensuring robustness and scalability.
Integrate front‑end components with server‑side logic and design APIs aligned with microservices and API‑driven architectures.
Implement data storage solutions across diverse databases, including document, relational, and semantic stores.
Contribute to secure system design by applying strong authentication, authorization, and encryption practices.
Build and optimize containerized services deployed on orchestrated cloud environments.
Perform code quality checks, security testing, and dependency management using industry‑standard tools.

Qualifications and Skills:

Strong expertise in back‑end development with technologies such as Vert.x, Kotlin, Java (>17), Spring Boot (WebFlux), and Hibernate.
Solid experience in microservices architecture, API‑driven development, and integration protocols such as AS4.
Proficiency with databases including MongoDB, PostgreSQL, Virtuoso Triple Store, and OpenSearch.
Hands‑on experience with Docker, Kubernetes, and cloud‑based CI/CD environments.
Deep understanding of security frameworks and tools such as OpenID Connect, OAuth2, TLS, and Keycloak.
Familiarity with SAST, DAST, Fortify, SonarQube, Sonatype, Dependency‑Track, Maven, and collaboration tools like JIRA, Confluence, Office 365, and SharePoint.

Halian Group:

With over 28 years of experience, we have come to understand that innovation is the only way to provide agile, practical solutions that transform businesses and careers.

Our resourcing and smart services help you to realize tomorrow’s potential. Discover the amazing things possible when you bring the right people and the right technologies together.

At Halian, we recognize that diversity, equity, and inclusion (DEI) are essential to building high-performing teams for our clients. We are committed to connecting organizations with top talent from all backgrounds, ensuring that every individual feels valued, respected, and empowered to contribute their unique perspectives. We encourage applications from all qualified candidates, regardless of race, gender, disability, or any other characteristic that makes them unique. By fostering diverse and inclusive workplaces, we help our clients drive innovation, enhance collaboration, and better reflect the communities they serve

BACK-END DEVELOPER in Brussels, Belgium

About the Company

We are Halian. Your partners in possibility. For over 27 years, we have been helping businesses make progress, build efficiency, and discover new possibilities. Our mission is to support talented individuals in their exploration, innovation, and unleashing of their full potential. We understand that innovation is the key to providing agile, practical solutions that transform businesses and careers at an accelerated pace. Halian's smart services, talent and search capability, help you to realise tomorrow's potential. We bel... Know more