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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Senior Developer (C#, ASP.NET MVC, JavaScript) - **Company:** The System - **Location:** Belfast, UK - **Experience:** Expert - **Salary:** £40,000.0 - £80,000.0 - **Contract:** Permanent contract - **Skills:** ASP.NET, HTML, JavaScript (Programming Language), .NET Framework, LTE (Telecommunication), Artificial Intelligence, Android Software Development, Application Integration Architecture, ASP.NET MVC Framework, Unit Testing, C Sharp (Programming Language), Cascading Style Sheets (CSS), Code Review, Github, Mobile Application Software, Model View Controller (MVC), Nunit, Scrum Methodology, Standard Sql, TypeScript, ReactJS, Backend, React Native, Software Version Control - **Published:** August 14, 2026 - **Apply:** https://www.adzuna.co.uk/jobs/details/5840202745 ## About the Role * Strong professional experience with C# and ASP.NET MVC * Strong SQL Server experience * Experience developing for the web using JavaScript, HTML, and CSS * Knowledge of principles for writing mobile apps and deploying to Apple and Android app stores * Experience using GitHub for source control and collaboration * Strong analytical and problem-solving skills at both a strategic and tactical level * Experience working with complex or long-lived codebases * Confidence contributing to technical design and making informed trade-offs * A pragmatic, calm approach when dealing with ambiguity or pressure * Clear communication skills, including explaining technical constraints to non-technical stakeholders * Significant commercial experience operating at senior developer level in both back-end and front-end areas * Desirable: experience with React Native or React, or equivalent frameworks * Desirable: experience writing automated unit tests using NUnit * Desirable: good understanding of waterfall, agile, and scrum development methodologies and their practical application * Desirable: experience in .NET 10 and other latest technologies including AI integration * Desirable: experience in TypeScript ## Description * Design, develop, and maintain software within the CIS Oncology (ChemoCare) product suite * Own complex features or technical areas through design, implementation, and handover into testing and release * Make technical decisions and escalate risks or trade-offs where needed * Contribute to the technical direction of the ChemoCare product suite, balancing near-term delivery with longer-term maintainability * Work closely with the QA team to support effective testing, defect resolution, and overall product quality * Ensure code is clear, maintainable, and appropriately tested in line with agreed development standards * Review code written by others and provide practical, constructive feedback * Support and mentor less experienced developers as part of normal team working * Provide 3rd line support as part of a shared team responsibility, including investigation and resolution of complex defects where required Technologies: * AI * ASP.NET * Android * C# * CSS * GitHub * Support * JavaScript * LESS * Mobile * MVC * React * React Native * SQL * Web * TypeScript, We create technology that connects care and improves outcomes across the NHS. Our CIS Oncology (ChemoCare) product plays a critical role in supporting chemotherapy treatment management nationwide, and we continue to invest in its safety, quality, and long-term evolution. This Senior Developer role sits within our CIS Oncology product suite and is a senior individual contributor position for an experienced hands-on developer. You will work on software that genuinely matters, alongside people who value collaboration, ownership, and integrity. 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