Salary: £45,000 - 70,000 per year Requirements: 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 Responsibilities: 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 Technologies: .NET Framework C# OWASP Oracle Python React SQL Security TypeScript ASP.NET AI Architect DevOps Support REST More: At Pontoon, we are an employment consultancy dedicated to improving everyones chance of being part of the workplace. We value expertise, energy, and enthusiasm in creating an inclusive environment that enables individuals from diverse backgrounds to thrive. We are currently seeking a senior C# Developer with a strong architectural focus to join our highly skilled engineering team in London. This is a 6-month initial contract role that requires on-site presence 3 days a week, with a competitive daily rate of £400 via umbrella. Join us in modernising legacy platforms and shaping the future of our technology estate. last updated 4 week of 2026