Senior .NET Developer Blazor UI focus

Mission Overview

Join Keystone Solutions as a Senior .NET Developer (Blazor, UI focus) on a consultancy mission at a client site. You will play a crucial role in building the future of public health technology, directly supporting digital services that enhance the health and wellbeing of millions. Your expertise will be essential in designing and delivering secure, accessible, and high-impact business applications, from the Blazor user interface to the .NET services behind it.

Key Responsibilities

• Provide technical leadership for the user interface, promoting a consistent approach to UI architecture and coding standards.
• Dedicate significant time to hands-on development of features, reusable components, and technical improvements using C#, modern .NET, Blazor, and Razor components.
• Design scalable and maintainable front-end structures that align with architectural principles.
• Build responsive user interfaces that meet accessibility standards and ensure usability across devices.
• Collaborate with analysts and UX stakeholders to clarify requirements and translate them into robust technical solutions.
• Integrate Blazor applications with REST APIs and ensure secure authentication and authorization flows.
• Maintain high code quality through structured reviews and testing practices.
• Utilize Git and Azure DevOps for version control and CI/CD pipelines.
• Coach and share knowledge with other developers, fostering a culture of technical excellence.
• Lead troubleshooting efforts for complex issues across development and production environments.
• Evaluate and recommend relevant technologies that align with architectural and security decisions.

Key Technical Expertise

• Advanced proficiency in C# and modern .NET development practices.
• Hands-on experience with Blazor applications and component lifecycle management.
• Strong command of HTML, CSS, and responsive design.
• Practical experience with web accessibility standards (WCAG 2.1 level AA).
• Proven experience with REST APIs and JSON exchanges.
• Experience implementing secure authentication using OAuth 2.0 and OpenID Connect.
• Working proficiency with Entity Framework Core and SQL.
• Strong experience with unit testing and automated UI testing.
• Advanced use of Git and Azure DevOps.
• Knowledge of AI-assisted development practices.

Key Soft Skills

• Technical leadership and mentorship abilities.
• Effective collaboration in a multidisciplinary environment.
• Strong problem-solving and decision-making skills.
• User-focused approach to digital experiences.
• Clear communication of complex technical matters.
• Resilience and adaptability to changing technologies.
• Commitment to continuous improvement and professional development.

Duration: 23/11/2026 - 31/12/2026 2 months • (full time)

Skills required

• Agile / ScrumConfirmed
• AI-assisted development (GitHub Copilot, Claude Code or similar)Junior
• Blazor and Razor components, including Blazor Web App render modesJunior
• C#Confirmed
• Entity Framework Core and SQLConfirmed
• Git, Azure DevOps and CI/CD pipelinesConfirmed
• HTML, CSS and responsive designConfirmed
• Modern .NET / ASP.NET CoreConfirmed
• OAuth 2.0 and OpenID Connect, JWT, claims-based authorisationConfirmed
• REST APIs and JSON exchangesConfirmed
• Testing: unit, component, integration and UI automationConfirmed
• Web accessibility, WCAG 2.1 AAJunior

Language requirements

• DutchActive knowledge
• EnglishActive knowledge
• FrenchActive knowledge