Our client is a leading European company specializing in internet infrastructure, located in the Brussels area. Join a dynamic, multicultural team at a tech-driven company with a human-scale approach. We are seeking a Senior Software Engineer (Java / Spring Boot ) to strengthen their development team and contribute to the architecture and evolution of mission-critical backend services. As a senior team member, you will contribute to shaping the technical foundation of Europe’s digital future. Key Responsibilities: • Design the backend architecture and define how components such as user interfaces, internal tools, and external applications interact with the backend, with a focus on reliability, resilience, and recovery. • Build services following microservices architecture principles and align with the Twelve-Factor App methodology for scalable, maintainable applications. • Develop, optimize and maintain high-quality backend systems using Java, Spring Boot, and modern development practices. • Contribute to solution architecture, applying patterns such as event-driven design, Saga, CQRS, and domain-driven design. • Design secure, scalable APIs and support data model evolution. • Model and manage data using relational databases, especially PostgreSQL, ensuring consistency, performance, and maintainability of the persistence layer. • Actively participate in Agile ceremonies such as planning, estimation, reviews, and retrospectives. • Lead technical design discussions and promote clean code, test-driven development, and automation. • Contribute to system modeling activities using appropriate standards (e.g. UML, ArchiMate) to describe services, integrations, and data flows. • Collaborate with product owners, business analysts, the service delivery manager, and the enterprise architect for planning activities and refining functional and non-functional requirements. • Work closely with DevOps and Security teams to ensure compliance with best practices and relevant regulations (e.g. NIS2, GDPR). • Provide mentorship to the team and share architectural and engineering expertise. • Continuously develop technical skills through training, reading, knowledge sharing, and staying informed about emerging technologies. • Degree in Computer Science, Information Technology, Engineering, or a related field.• 7 years of backend development experience with Java and Spring ecosystem. • Proven experience in solution architecture. • Experience delivering features in agile environments. Technical Proficiencies: • Strong knowledge of Java, Spring Boot, Spring Security, and RESTful API development. • Experience with event-based architecture, Kafka, RabbitMQ, and eventual consistency patterns. • Proficiency in RDBMS, especially PostgreSQL, and ORM tools. • Familiarity with CI/CD pipelines, Git workflows, and tools such as Bamboo, Jenkins, GitLab CI. • Testing mindset: solid experience in unit, integration, and contract testing. • Experience with containerization tools like Docker; knowledge of Kubernetes is an asset. • Familiarity with system modeling practices, such as UML, ArchiMate, or equivalent standards to support architectural design and documentation. • Experience with Atlassian tool stack, especially Jira for backlog management and Confluence for technical and project documentation. • Exposure to observability tools such as Prometheus, Grafana, is a plus. Soft Skills: • Excellent communication and collaboration skills. • Strategic thinker with strong problem-solving and analytical abilities. • Able to mentor others and promote a culture of continuous improvement. • Fluent in English (spoken and written). • A dynamic and international work environment. • A competitive compensation package that includes a competitive salary, a company car, meal vouchers, a comprehensive group and health insurance plan and additional holidays. • Healthy work-life balance including hybrid work. • Opportunities for growth and development. • A role that supports a high-impact, high-visibility European digital initiative.