Senior Fullstack Java Developer

Senior Fullstack Java Developer - Brussels, Belgium

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About the Role

RELYzIT Talent is seeking a Senior Fullstack Java Developer for our client, a leading organization undergoing a major IT transformation. This freelance opportunity places you at the heart of a mission-critical modernization, where your expertise will directly impact the evolution of essential public services. You’ll be instrumental in bridging legacy systems with cutting-edge cloud architectures, ensuring robust, scalable, and secure solutions that matter to millions.

Why This Role Matters

This is not just another development role. You will be a key builder in a high-stakes environment, modernizing complex systems that underpin vital regulatory and financial processes. Your work will drive the reduction of technical debt, enable cloud adoption, and ensure compliance with evolving standards like NIS2. The future of digital public services depends on the solutions you help create, harmonize, and secure.

What You’ll Be Doing

• Designing, developing, and adapting high-performance, user-centric IT applications for critical business domains
• Analyzing technical specifications and selecting optimal solutions for both large-scale and smaller projects
• Conducting technical analyses within business projects, ensuring architectural consistency across legacy and modern systems
• Advising on integrations, data models, performance, scalability, and best practices in cloud and hybrid environments
• Supporting teams in adopting new technologies, architectural patterns, and resilient, high-availability solutions
• Resolving complex technical challenges in a highly interconnected, regulated environment
• Ensuring compliance with security standards, including NIS2, and maintaining a seamless bridge between legacy and modern components

Technical Skills

• 5–7+ years of experience in complex IT programming environments
• Expertise in modern Java (Spring, Spring Boot, microservices, API-driven, event-driven architectures)
• Advanced skills in containerization and orchestration (OpenShift, Docker)
• Strong command of relational databases (MySQL), data modeling, and Flyway
• Proficiency in integrations: messaging, REST, GraphQL, event-driven systems
• Experience with resilient, high-availability, and hexagonal architectures
• Deep understanding of security standards and regulatory compliance (NIS2)
• Front-end expertise with Angular or ReactJS
• Expert-level with IntelliJ, Maven, Git, JUnit, SonarQube, Swagger/OpenAPI
• Experience with Atlassian Stack (Jira, Confluence), NPM, IBM WebSphere, JSF, Lombok
• Expertise in Agile/Scrum methodologies
• Experience working within federal public service environments is highly valued

Language Proficiency

• Excellent command of French, Dutch, and English (written and spoken)

Other Requirements

• Master’s degree in IT or equivalent professional experience
• Demonstrated ownership, autonomy, and proactive problem-solving mindset
• Exceptional analytical, synthesis, and communication skills
• Ability to connect business needs with technical solutions and maintain a global vision
• Quality-driven, structured, and educational approach to team collaboration
• Remote work possible (up to 2 days per week) after initial on-site onboarding

Project Details

• This is a freelance position based in Brussels, Belgium
• Engage in a high-impact, long-term transformation project with a leading public sector client
• Join a community of elite builders, recognized and credentialed through RELYzIT’s VECTOR7™ Signal Stack

Ready to build the future with us? Upload your CV now and join the RELYzIT Talent community of elite builders.