Senior Java Developer

We are looking for an experienced Senior Java Developer to join a multidisciplinary Agile team responsible for the design, development, and maintenance of business-critical railway infrastructure systems. These applications are central to train traffic planning, infrastructure works, and operational safety, running in a 24/7 production environment.You’ll work in a Agile way, collaborating with product owners, testers, and fellow developers to build robust, high-performing applications that directly impact mobility and infrastructure reliability across Belgium.Key ResponsibilitiesTechnical Analysis: Translate business requirements into efficient and maintainable technical designs.Development: Build and enhance backend solutions using modern Java and the Spring ecosystem.Maintenance & Support: Ensure the stability and performance of complex, interdependent applications.Bug Fixing & Troubleshooting: Diagnose and resolve issues quickly and efficiently.Test Automation: Implement unit and integration tests (JUnit, Mockito) and integrate them into CI/CD pipelines.Documentation: Maintain clear, up-to-date technical and architectural documentation.Deployment: Contribute to release management and deployments in on-premise environments.Code Quality: Promote clean code practices, SOLID principles, and secure coding standards.Mentorship: Guide and coach junior developers, sharing best practices and technical insights.On-Call Support: Participate in a 24/7 rotation after a full training period (approximately one week per month).What are we looking for?Must-Have SkillsJava (min. v8) – 10+ years of hands-on development experience.Spring Framework (Boot, Core, MVC) – 10+ years, expert-level knowledge.Hibernate / JPA – Advanced ORM and data access expertise.SQL Databases – Strong experience with PostgreSQL, MySQL, or Oracle (optimization, tuning, stored procedures).Test-Driven Development (TDD) – Strong command of JUnit, Mockito, and automated testing practices.CI/CD Tools – Practical experience with Git, Jenkins, and Artifactory.DevOps Mindset – Understanding of automation, infrastructure, and release management principles.Fluent in French or Dutch (C1) with good knowledge of the other national language (B1 minimum).Nice-to-HaveExperience with on-premise deployments and infrastructure automation.Knowledge of containerization (Docker, OpenShift) or monitoring tools.What do we offer?Location: Brussels (hybrid working model)Contract: Freelance or PermanentStart Date: January 1, 2026Duration: Through December 2030 (renewable annually)