Senior Backend .NET Developer

Senior Backend .NET Developer - 3 months - Brussels Belgium

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About the Role

RELYzIT Talent is seeking a Senior Backend .NET Developer for a high-impact freelance assignment with our client in Brussels. This is a unique opportunity to join a team of elite builders shaping the next generation of core business applications. You’ll be at the heart of digital transformation, delivering robust, scalable solutions that drive real business outcomes. If you thrive in environments where your expertise shapes the future, this is your stage.

Why This Role Matters

Our client is evolving their core business platforms to meet the demands of a rapidly changing market. As a Senior Backend .NET Developer, you will be instrumental in translating complex business needs into technical solutions that are reliable, maintainable, and future-proof. Your work will directly impact operational efficiency, user experience, and the organization’s ability to innovate at scale. This is your chance to leave a lasting mark on mission-critical systems.

Key Responsibilities

• Interpret and implement UML and BPMN models to guide application architecture and workflows


• Design, develop, and maintain RESTful services using .NET Framework and .NET 8+


• Build and enhance interfaces in ASP.NET WebForms, MVC, and .NET 4.5+


• Manage and optimize SQL Server databases (2016–2025) and Oracle 19 environments


• Apply design patterns as recommended by solution architects to ensure scalable, maintainable code


• Develop and consume APIs using WebAPI, WCF REST, WCF, and Web Services


• Work with XML and JSON data formats, adhering to W3C standards


• Utilize Azure DevOps for CI/CD, leveraging GIT and TFVC for version control


• Leverage Entity Framework Core for data access and persistence


• Analyze functional requirements and translate them into robust technical solutions in collaboration with scrum teams and architects


• Ensure code quality through unit testing, code reviews, and adherence to SOLID principles


• Participate in corrective and evolutionary maintenance of existing applications


• Diagnose and resolve technical incidents, driving continuous improvement initiatives


• Contribute actively in Agile/Scrum ceremonies and foster a collaborative team environment

Technical Skills

• Expertise in .NET and .NET Core development


• Proficiency with ASP.NET, ASP.NET MVC, and Visual Studio


• Advanced knowledge of RESTful API design and implementation


• Strong experience with SQL Server (2016–2025) and Oracle 19


• Hands-on with Azure DevOps, GIT, and TFVC


• Entity Framework Core expertise


• Solid understanding of JSON, XML, and W3C standards


• Familiarity with WebAPI, WCF REST, WCF, and Web Services


• Experience with Redgate tools is a plus


• Knowledge of UML and BPMN modeling (nice to have)


• Deep understanding of SOLID principles and object-oriented best practices


• Experience in Agile/Scrum environments


• Unit testing and code review experience


• Soap API experience is a plus

Language Proficiency

• Fluency in French is essential (the team operates predominantly in French)

Other Requirements

• Autonomous, analytical, and proactive approach to development tasks


• Strong problem-solving skills and a quality-driven mindset


• Excellent communication and teamwork abilities


• Ability to collaborate effectively with analysts, architects, and fellow developers


• Experience in both corrective and evolutionary maintenance of business applications

Project Details

• Freelance position


• 3-month initial contract


• Partial remote work (onsite presence in Brussels required as per project needs)

Ready to build the future with RELYzIT Talent? Upload your CV now and join a community where elite builders shape what’s next.