Java Software Engineer

One of our leading banking partners is looking for a freelance Backend Java Engineer to take technical ownership of a legacy core lending system and support its evolution. This isn’t greenfield: it’s a real challenge for a real engineer who thrives in complex codebases and can strike a balance between modernisation and stability.

Logistics:

• Position: Freelance Backend Java Developer (Legacy Systems Specialist)
• Duration: 24-Month Contract
• Location: Brussels (Hybrid - 2 days/week onsite)
• Languages: English (French or Dutch is a bonus, not a must)
• Start Date: ASAP
• Day Rate: €(Negotiable & Competitive)

Core Responsibilities:

• Maintain and incrementally modernise a core lending system built on a legacy Java stack
• Design, refactor, and evolve Java components using Spring (non-Boot)
• Interface with XML-based integrations and SOAP web services
• Handle message-driven workflows using Kafka
• Collaborate with cross-functional teams to maintain quality, stability, and incremental improvements
• Work closely with technical leads on technical debt reduction and architecture improvements

Essential Skills:

• 6+ years of Java development experience, especially in large-scale enterprise systems
• Strong command of core Spring (non-Boot), object-oriented design, and clean code principles
• Hands-on experience with SOAP services and XML-based communication
• Familiarity with Kafka and Kubernetes in production environments
• Ability to work in a CI/CD-driven environment using Git, GitLab, Jenkins, SonarQube
• Solid understanding of legacy systems: how to respect them, work with them, and gradually improve them

Desirable Skills:

• Experience with Domain-Driven Design or hexagonal architecture
• Knowledge of Oracle databases and service bus architectures
• Familiarity with Fortify, Nexus, and other security/dependency tools
• Past exposure to modernising monolithic applications without destabilising them

What You Bring:

• Technical patience - you understand that working on legacy isn’t glamorous, but it’s critical
• Curiosity - you ask “why” before you rip and replace
• Team spirit - this is a collaborative squad that values input
• Problem-solving - deep-diving into decades-old code doesn’t scare you

Why This Role Matters:

This isn’t a typical Java contract. You’ll be touching the core of a system that handles critical banking operations - used by thousands, shaped over years, and in need of careful, expert handling.

Interested? Let’s talk. This is a key hire for one of Belgium’s most trusted financial players - and a chance to do meaningful technical work at scale.