Senior Software Engineer

Referment is working with a regulated payments business to hire a Senior Software Engineer focused on modernising established systems. The challenge is to make complex C# and SQL logic easier to understand and maintain while keeping revenue-critical services running safely. You will work across legacy and modern .NET, extracting business rules into tested components and improving the services around them. This is a role for someone who enjoys understanding why an existing system behaves as it does before changing it, rather than starting with a wholesale rewrite. The Role Trace business rules through C#, JavaScript and SQL stored procedures, then separate them into components that can be tested independently.Build services with clear dependency management, access controls and logging so their behaviour can be understood in production.Investigate problems across APIs, data processing and messaging, including failures caused by the way systems interact.Compare new calculations with existing outcomes in shadow mode before allowing changes to affect live processing.Refactor SQL Server logic carefully, preserving the correctness of client-money handling. What We're Looking For Senior hands-on experience with .NET 6+ and .NET Framework 4.8, including MVC5, WebAPI 2 and Entity Framework 6.Deep SQL Server experience and confidence reading and safely changing complex stored procedures.Working JavaScript or TypeScript knowledge and the ability to follow behaviour across application and database code.A measured approach to modernisation, using tests and comparison of outputs to demonstrate that changes are safe. Useful Additional Experience Experience with AWS Lambda, SQS, SNS or RDS would help. This could suit a senior .NET engineer who finds satisfaction in untangling established systems and improving them incrementally, with correctness taking priority over a particular architectural fashion. #Referment