Senior .NET Developer

Inetum; Brussel; Hybrid; EUR 70,000 - 110,000; Full time

Benefits offered by this job

Hybrid work environment

3 days onsite

Long-term assignment

Job summary

Inetum in Belgium (Brussels region) seeks a Senior .NET Technical Developer with a strong architectural background who enjoys hands-on development. You will shape the evolution of a large-scale internal platform, driving modernization and architectural improvements while remaining actively involved in coding.

You will collaborate with business stakeholders and development teams, lead refactoring efforts, and ensure secure, high-performance solutions within a complex legacy environment.

Qualifications

• Senior .NET developer with strong architectural background.
• 10+ years in Microsoft development environments.
• Proven modernization and migration project experience.
• Strong knowledge of C#, .NET, and ASP.NET MVC.
• Experience with REST APIs, SQL Server, and legacy systems.
• Excellent communication with technical and business stakeholders.

Responsibilities

• Hands-on development within a .NET environment.
• Analyze and improve existing architecture.
• Lead refactoring initiatives to reduce technical debt.
• Identify and resolve performance and security issues.
• Advise on technical decisions and modernization efforts.
• Design future-proof solutions within current infrastructure.
• Guide technical stakeholders and collaborate with business teams.
• Contribute to migration and continuous improvement programs.

Skills

C# & .NET

ASP.NET MVC

REST APIs

SQL Server

Architecture leadership

Legacy modernization

Stakeholder management

English (written/spoken)

Dutch (written/spoken)

Tools

Azure

IIS hosting

WCF

ETL/Integration

Job description

• Hands-on development within a .NET environment


• Analyze and improve existing architecture


• Reduce technical debt and lead refactoring initiatives


• Identify and resolve performance and security issues


• Advise on technical decisions and modernization initiatives


• Design future-proof solutions within an existing environment


• Challenge and guide technical stakeholders


• Collaborate closely with business stakeholders and development teams


• Contribute to migration and continuous improvement programs

Profile

Your Profile

You are a senior developer with a strong architectural background who enjoys remaining actively involved in development.

Must-Have

• Minimum 10 years of experience in Microsoft development environments


• Strong knowledge of C# and .NET


• Experience with ASP.NET MVC


• In-depth knowledge of .NET Framework environments


• Experience with modern .NET (.NET 6/7/8)


• Strong SQL Server expertise


• Experience with REST APIs and systems integration


• Experience working within complex legacy environments


• Proven track record in modernization and migration projects


• Strong analytical and problem-solving skills


• Excellent communication skills with both technical and business stakeholders


• Dutch: professional working proficiency (spoken and written)


• English: professional working proficiency (spoken and written)

Nice to Have

• Experience with Azure


• Knowledge of IIS hosting


• Experience with WCF


• Experience with workflow or integration platforms


• Knowledge of ETL processes or job scheduling solutions


• Experience with performance optimization


• Knowledge of secure software development practices

Who Are We Looking For?

You are someone who:

• Quickly understands technical complexity


• Works independently


• Takes ownership and responsibility


• Is confident in constructively challenging technical decisions


• Has strong stakeholder management skills


• Remains pragmatic without compromising quality


• Enjoys bridging the gap between business and IT

About Inetum

Flemish Brabant / Brussels Region
Hybrid (3 days onsite)
Long-term assignment
Freelance

About the Assignment

For an organization operating a complex, business-critical application landscape, we are looking for an experienced Senior .NET Technical Developer who enjoys combining hands‑on development, technical leadership, and modernization initiatives.

You will join a team responsible for the continued development and evolution of a large‑scale internal platform with a long history. In addition to delivering new functionalities, you will play a key role in driving improvements in architecture, performance, security, and maintainability.

This role is ideal for someone who takes ownership, embraces technical challenges, and is energized by improving complex application environments.

Additional Information

Practical Information

• Hybrid working environment


• 3 days onsite presence required


• Full-time engagement


• Short-term start possible


• Long-term assignment with stable future prospects

Interested?

Are you an experienced .NET professional looking to make a real impact in a challenging and evolving environment? We would be pleased to discuss this opportunity with you in a confidential conversation.

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