Mendix Legacy Application Modernization Developer

Mendix Legacy Application Modernization Developer - 25 months - Brussels, Belgium

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About the Role

RELYzIT Talent is seeking a Mendix Legacy Application Modernization Developer for a high-impact, freelance assignment with our client in Brussels. This is a unique opportunity to lead the transformation of a mission-critical legacy application into a future-proof, low-code platform. You’ll be at the forefront of technical innovation, leveraging AI, code analysis, and model-driven development to deliver a robust, scalable solution that will shape the digital backbone of a major organization.

Why This Role Matters

Our client’s legacy application, built in Adobe ColdFusion and spanning over 150,000 lines of code across 20 modules, is the core of their operations. Modernizing this system is essential to ensure agility, maintainability, and long-term value. As the Application Architect/Technical Lead, you will drive the migration to a modern low-code platform, maximizing reuse of existing business logic and architecture. Your expertise will directly impact the efficiency, quality, and future-readiness of the organization’s digital landscape.

Key Responsibilities

• Design and own the technical architecture for the modernization of a large-scale legacy application to a Mendix-based low-code platform.
• Review and validate AI-generated Mendix components, ensuring alignment with business logic and technical standards.
• Establish and enforce development standards, best practices, and code quality benchmarks for the project team.
• Conduct in-depth code reviews and provide technical coaching to developers, fostering a culture of excellence and continuous improvement.
• Architect integration solutions and design robust security frameworks for the new platform.
• Leverage innovative, automated migration methodologies, including AI, code analysis, and model-driven development, to accelerate and control the migration process.
• Document and communicate architectural decisions, ensuring transparency and alignment across multidisciplinary teams.
• Deliver standalone, production-ready modules at the end of each project phase, enabling incremental value delivery.
• Collaborate closely with business stakeholders, product owners, and technical teams to ensure solutions meet both current and future needs.
• Support the preparation of vision memos and technical documentation, demonstrating the value and success of proposed solutions.

Technical Skills & Experience

• Expertise in Application Architecture, with a proven track record of designing and delivering enterprise-grade solutions.
• Confirmed experience with Mendix development and low-code architectures.
• Hands-on experience in migrating legacy applications, processes, and data to new platforms.
• Familiarity with AI-assisted development and automated code analysis tools.
• Strong background in Agile/Scrum methodologies, with the ability to lead multidisciplinary teams in dynamic environments.
• Experience with enterprise applications and large-scale system integrations.
• Technical leadership in establishing development standards, conducting code reviews, and mentoring teams.
• Demonstrated ability to deliver innovative, high-quality solutions within complex project frameworks.

Language Proficiency

• Professional proficiency in English is required.
• Knowledge of French or Dutch is a strong advantage.

Other Requirements

• All relevant certificates and supporting documents must be attached to your CV and will be validated as part of the selection process.
• Ability to work partially remote, with on-site presence in Brussels as required.
• Availability for a 25-month freelance assignment, with potential for extension based on project needs and budget approval.
• Demonstrated experience in successfully applying proposed modernization solutions in previous or ongoing projects.
• Commitment to delivering standalone, value-driven deliverables at each project phase.

Who You Are

• A builder at heart, driven by impact and innovation.
• Ownership-oriented, proactive, and passionate about solving complex technical challenges.
• Collaborative, communicative, and eager to mentor and elevate those around you.
• Ready to join a community of elite tech talent and shape the future of digital transformation.

Ready to build the future? Upload your CV and supporting documents now to join RELYzIT Talent’s elite network and make your mark on this transformative project.