Freelance Senior.NET Developer

Tasks and responsibilities

Within a public-sector digital-services setting, you will create secure, accessible and responsive business applications for citizens, healthcare professionals and internal users in Belgium. Your work will cover the full application stack, including the Blazor user interface and the .NET services supporting it, while you also contribute to technical choices and assist colleagues.

You will become part of an ICT department with around 250 professionals and more than 50 projects at varying stages of development. The organisation is moving its application landscape towards a cloud-native architecture on Microsoft Azure, with Azure Service Bus and containerised workloads. Shared libraries, the design system, DevOps pipelines and application-team standards are supplied by a platform engineering team.

Blazor is the standard for web user interfaces, enabling a single .NET skill set to span the entire application. Because citizens, healthcare professionals and employees use the UI directly, accessibility, consistency and responsiveness are essential. The organisation is additionally investigating responsible applications of AI in business software and its development.

Job purpose

In this Senior .NET Developer role with a UI focus, you will design, build, integrate and maintain contemporary business applications. You will own their user interfaces and also contribute to the services underneath them. Alongside advanced hands-on coding, the position involves technical leadership, coaching and close cooperation with analysts, architects, UX stakeholders, security specialists, the platform engineering team and operations.

You will convert functional and technical requirements into reusable and accessible solutions. This includes delivering a consistent experience across browsers and devices, integrating services and APIs correctly, reusing the shared component library and design system, and meeting standards for architecture, security, quality, maintainability and delivery.

Complex technical problems will be addressed with your input as a senior developer, together with justified design decisions, improved engineering practices, coaching and code reviews. The position is decidedly hands-on, involving direct work on features, testing, troubleshooting and ongoing improvement of both the UI and the services supporting it.

Key responsibilities

• Set technical direction for Blazor development across teams and encourage consistent UI architecture, reusable components, coding standards and engineering practices that follow the platform team's standards.
• Use C#, modern .NET, Blazor, Razor components and the dependent .NET Web APIs to deliver features, reusable components, prototypes, technical enhancements and bug fixes.
• Create scalable, maintainable and reusable front-end structures in accordance with the organisation's architectural principles, and help develop the shared component library based on MudBlazor and the shared design system.
• Develop responsive interfaces using semantic HTML and modern CSS that satisfy WCAG 2.1 level AA, as required for Belgian public bodies by the European Web Accessibility Directive. Usability, browser compatibility and the public-service context must remain considerations throughout development.
• Collaborate with functional and business analysts and UX stakeholders to refine requirements, judge feasibility and turn user and business needs into robust technical solutions.
• Connect Blazor applications to REST APIs and JSON-based services, using typed clients, appropriate error handling, state management, validation and resilience. Extend the Web APIs where features call for it.
• Apply secure development practices throughout the application lifecycle and implement authentication and authorisation flows with OAuth 2.0 and OpenID Connect for internal users, healthcare professionals and citizens, each using its own identity provider.
• Keep code quality high through structured pull-request reviews, refactoring, SonarQube static analysis, coding standards and components that are clear, reusable and testable.
• Establish and maintain unit tests, Blazor component tests with bUnit, service-level integration tests and, when suitable, automated UI tests with Playwright. Use the test pyramid to enable dependable releases and avoid regressions.
• Use Git, Azure DevOps repositories, boards and CI/CD pipelines to manage versioning, automated builds, testing and deployment to Azure environments in a controlled way.
• Choose the suitable Blazor render mode for each application, analyse and enhance loading time, rendering behaviour and responsiveness, and investigate test and production issues with Dynatrace and browser tools.
• Support developers through coaching, share expertise in Blazor and accessibility, document