Shieldpay is seeking a Senior Software Engineer who thrives at untangling complex systems and modernising core infrastructure without downtime. The role focuses on modernising core C#/SQL systems and requires working across both legacy .NET Framework 4.8 (ASP.NET MVC5, WebAPI2, EF6) and modern .NET (6+) as they coexist during the transition. You will extract business rules from C#, embedded JavaScript, and undocumented SQL stored procedures into clean, tested rule assemblies; build new services with proper Dependency Injection, robust authentication/authorization, structured logging, and full observability. You will operate across multiple systems such as the API façade, ETL pipeline, and SNS/SQS event bus, deploying changes via shadow-mode verification to prove equivalence before going live. You will refactor and optimise heavy SQL Server stored procedures to preserve client-money correctness. Nice-to-haves include AWS Lambda, SQS, SNS, and RDS, and comfort working with an in-house AI-agent orchestrator that supports SDLC automation. The position is based in City of London, United Kingdom, and offers hybrid work arrangements.

Shieldpay is seeking a Senior Software Engineer who thrives at untangling complex systems and modernising core infrastructure without downtime. The role focuses on modernising core C#/SQL systems and requires working across both legacy .NET Framework 4.8 (ASP.NET MVC5, WebAPI2, EF6) and modern .NET (6+) as they coexist during the transition. You will extract business rules from C#, embedded JavaScript, and undocumented SQL stored procedures into clean, tested rule assemblies; build new services with proper Dependency Injection, robust authentication/authorization, structured logging, and full observability. You will operate across multiple systems such as the API façade, ETL pipeline, and SNS/SQS event bus, deploying changes via shadow-mode verification to prove equivalence before going live. You will refactor and optimise heavy SQL Server stored procedures to preserve client-money correctness. Nice-to-haves include AWS Lambda, SQS, SNS, and RDS, and comfort working with an in-house AI-agent orchestrator that supports SDLC automation. The position is based in City of London, United Kingdom, and offers hybrid work arrangements.