We are seeking a highly skilled Senior Fullstack Developer to join our client’s team in Brussels. You’ll own end-to-end development of large-scale applications, spanning back-end Java services and a modern React front-end. You’ll collaborate with product owners, architects, and cross-functional teams to design, implement, optimize, and deploy high-performance software.

What you’ll do

• Design and develop high-performance, scalable applications using Java, Maven, and frameworks such as Quarkus or Spring.
• Architect and optimize MongoDB and PostgreSQL schemas, queries, and indexing to ensure low latency and high throughput.
• Build and scale microservices and event-driven systems using Kafka; integrate with the ELK stack for logging, monitoring, and troubleshooting.
• Identify bottlenecks and lead performance optimization efforts across code and database layers; implement profiling and tuning strategies.
• Drive DevOps practices: CI/CD pipelines with Jenkins, SonarQube, and Nexus; emphasis on automation, security, and deployment efficiency.
• Implement secure coding practices, vulnerability management, and compliance throughout the development lifecycle.
• Collaborate with cross-functional teams and stakeholders; analyze requirements, provide technical guidance, and drive solutions to completion.
• Mentor junior developers and promote a culture of continuous improvement.
• End-to-end ownership: analyze, design, implement, test, and deploy tasks with minimal supervision; take ownership of codebases when needed.
• Frontend development with React (TypeScript), webpack, ES6+, UI built with Ant Design; testing with Jest and React Testing Library.
• Work with MinIO or similar bucket-based storage; manage authentication/authorization (RBAC) and token-based security (JWT).

Required qualifications

• Strong experience with Java, Maven, and building large-scale applications using Quarkus or Spring.
• Deep expertise with MongoDB and PostgreSQL, including performance-oriented data access and indexing.
• Proven experience with Kafka for event-driven architectures and ELK stack for monitoring/troubleshooting.
• Solid knowledge of performance profiling and optimization for both code and database layers.
• Proficient in Docker, Kubernetes, Jenkins, SonarQube, and Nexus (DevOps / CI-CD focus).
• Security-minded: secure coding practices, vulnerability management, and compliance awareness.
• Excellent communication and collaboration skills; ability to work with product owners, architects, and engineers.
• Experience with Agile methodologies and delivering software in iterative cycles.
• Exposure to performance profiling tools and security tooling (e.g., Snyk, OWASP).
• Proactive, independent mindset with a track record of taking ownership of tasks end-to-end.
• Frontend: React with TypeScript, webpack, ES6+; UI with Ant Design; testing with Jest and React Testing Library.
• MinIO or similar bucket-based storage experience.
• Knowledge of RBAC and JSON Web Tokens (JWT) for authentication/authorization.

Nice-to-have

• Bitbucket experience (Git) is a plus.
• Experience taking over a codebase with minimal handover.
• Familiarity with additional cloud environments (AWS/Azure/GCP) and related tooling.

Location and start

• Location: Brussels, Belgium (hybrid option available)
• Start date: November

If you’re excited by building scalable, secure, end-to-end solutions and leading the charge from design to deployment, we’d love to hear from you.