Senior Full Stack C#.NET Developer

Senior Full Stack C# .NET DeveloperFully Remote (UK Residents Only)About WebX SystemsAt WebX, we specialise in technical publishing and content management solutions for the aerospace and defence sectors worldwide. Our flagship products—UltraCSDB®, UltraAuthor™, UltraXML™, and UltraPortal™—are used globally and combine proven legacy systems with cutting-edge, cloud-native innovations.As a privately owned UK business, we take pride in delivering exceptional software and highly responsive support. Joining our close-knit team means your work has direct and meaningful impact. We work closely with customers to ensure our solutions meet their exact requirements. Join us on our journey to become the global leader in aerospace and defence content management.Role OverviewWe\’re looking for a proactive, experienced Senior Full Stack .NET Developer to help evolve our product suite. You’ll work across both legacy Windows desktop applications and modern web-based systems and help lead the transition toward cloud-native architecture. This role is perfect for someone who enjoys innovating within established environments while also driving forward new development.Technology StackLegacyC#, .NET Framework, WinForms, WCFClient-Server Architecture, MS SQL ServerModern.NET 9, Blazor, Minimal APIsEntity Framework, Redis, RabbitMQAspire (.NET), Cloud-Native developmentKey ResponsibilitiesProject Leadership – Lead projects from concept to deployment, collaborating with senior developers and the technical director to design and implement architectural and technical solutions.Full Stack Development – Maintain and enhance both legacy desktop applications and modern browser-based web apps.Legacy-to-Modern Migration – Help drive the migration from WinForms to Blazor-hosted cloud solutions.Code Quality & Testing – Write clean, maintainable, well-tested code, and conduct peer reviews.Problem Solving – Design robust, scalable solutions to complex challenges.Customer Collaboration – Communicate effectively with non-technical stakeholders to translate business needs into technical requirements.Continuous Improvement – Proactively refactor and optimise existing codebases; contribute to internal documentation.Required Skills & Experience5+ years of commercial experience in C# and .NET.Expertise in:.NET Framework and WinFormsModern .NET (.NET 9)SQL Server (including performance optimisation)Front-end tech (HTML, CSS, JavaScript)Proven experience with application modernisation, including migrating legacy WinForms applications to modern web platforms (Blazor preferred).· Strong understanding of layered architecture and best practices in software design.Proven ability to deliver complex software projects independently.Strong analytical and problem-solving skills.Excellent written and verbal communication, with the ability to explain technical topics to business stakeholders.Degree in Computer Science or related field (or equivalent experience).Bonus Points ForExperience with Blazor and RESTful/API-first developmentFamiliarity with Azure or other cloud platformsUnderstanding of .NET Aspire and containerisation (e.g. Docker)CI/CD pipelines, DevOps practicesOAuth/OpenID Connect authenticationApplication modernisation or migration workXML/XSLT and publishing workflowsFamiliarity with ASD S1000D, ATA iSpec 2200, or related aerospace/defence standardsExperience using AI-based coding assistants (e.g. Claude, ChatGPT, GitHub Copilot) to boost productivity and code quality.What We OfferSalary: £70,000 – £85,000 depending on experienceTechnical Growth – Work across a diverse technology landscape, from legacy systems to cutting-edge cloud-native tools.Autonomy – Freedom to shape technical decisions and make a significant impact on product direction and architecture.Career Advancement – Opportunities to progress and grow as you help lead the next phase of our technology evolution.Work-Life Balance – Fully remote role with flexible working arrangements to support your productivity and well-being.Professional Development – Dedicated budget and support for ongoing training, certifications, and learning new technologies.Competitive Benefits – Workplace pension, annual leave that increases with tenure, and a supportive culture for professional growth.Team & CultureWe’re a small, collaborative, and fully remote team. We value async-first communication and structured collaboration. Everyone’s contribution matters, and ideas are heard, tested, and implemented rapidly.Interview ProcessIntroductory video callTechnical assessment (take-home or timed)Technical interview with real-world problem-solvingFinal interview with company leadershipLocationUK-based applicants onlyFully remoteEquipment provided