Pontoon is an employment consultancy. We put expertise, energy, and enthusiasm into improving everyone's chance of being part of the workplace. We respect and appreciate people of all ethnicities, generations, religious beliefs, sexual orientations, gender identities, and more. We do this by showcasing their talents, skills, and unique experience in an inclusive environment that helps them thrive. C# Developer (Architecture Focused) London, 3 days per week on site required 6-month initial contract £400.00 via umbrella per day The Opportunity We're looking for a senior C# Developer with a strong architectural focus to join a highly skilled engineering team working on business-critical systems at scale. This role sits at the heart of a major technology estate and offers the chance to modernise legacy platforms, shape technical direction, and contribute to secure, high-performance solutions. You'll work across both transformation initiatives and greenfield development, collaborating closely with engineering, DevOps, DBAs, and governance teams in a structured, enterprise environment. What You'll Be Doing Designing and developing applications using .NET Framework / .NET Core, React / TypeScript, Python, and relational databases Refactoring and modernising legacy systems to reduce technical debt and improve performance and reliability Embedding modern security patterns across APIs and services (authentication, authorisation, OWASP controls, secure access) Contributing to greenfield solutions, ensuring scalability, maintainability, and security from day one Optimising SQL Server and Oracle databases and supporting safe releases through change management processes Supporting production systems and collaborating across global technology teams What We're Looking For Strong experience with C#.NET in complex or enterprise environments Proven ability to modernise legacy applications Good architectural understanding and secure development mindset Experience with SQL Server and/or Oracle Comfortable working across the full SDLC in a controlled environment Candidates will ideally show evidence of the above in their CV to be considered please click the "apply" button. We use generative AI tools to support our candidate screening process. This helps us ensure a fair, consistent, and efficient experience for all applicants. Rest assured, all final decisions are made by our hiring team, and your application will be reviewed with care and attention. Please be advised if you haven't heard from us within 48 hours then unfortunately your application has not been successful on this occasion, we may however keep your details on file for any suitable future vacancies and contact you accordingly