Senior .NET Backend Developer – ASP.NET Core & SQL Server

About the role

Rausch Sturm LLP is seeking a senior .NET developer to own the backend and data layer of its business systems. You will design, build and maintain ASP.NET Core APIs, background services and the T‑SQL code that powers them, ensuring correctness for regulated PCI‑DSS data.

Key responsibilities

• Design, develop and maintain ASP.NET Core Web APIs (REST, OpenAPI/Swagger, versioning) for internal and partner integrations.
• Write, tune and maintain T‑SQL objects (stored procedures, functions, views, indexes) across a large SQL Server estate; diagnose and optimise slow queries.
• Build and support background processing including Windows services.NET worker services, Quartz‑scheduled jobs and Azure Functions (including Durable Functions).
• Implement document automation pipelines: PDF generation, splitting, merging, redaction, stamping and OCR using Aspose, QuestPDF, Tesseract/IronOCR, and generate Excel reports.
• Manage schema changes via Flyway migrations in Azure DevOps, ensuring no ad‑hoc production changes.
• Instrument applications with structured logging (Serilog), telemetry (Azure Application Insights) and set up alerting.
• Maintain and improve existing applications and database code, providing ongoing support and production incident response.
• Prioritise tasks dynamically to address production escalations, client deadlines and cross‑team requests.

Required profile

• Proven senior‑level experience developing backend systems with .NET and SQL Server.
• Strong analytical skills to diagnose performance issues and production incidents.
• Ability to work under pressure, triage escalations and shift priorities quickly.
• Experience with regulated data environments (PCI‑DSS) is a plus.

Required skills

• C# and .NET (including .NET 8/9 and legacy frameworks)
• ASP.NET Core Web API, OpenAPI/Swagger, API versioning
• T‑SQL, stored procedures, functions, views, indexes on Microsoft SQL Server
• Azure Functions, Durable Functions, Azure API Management
• Windows services.NET worker services, Quartz scheduler
• Flyway migrations, Azure DevOps
• Serilog, Azure Application Insights
• PDF processing (Aspose, QuestPDF), OCR (Tesseract, IronOCR)
• Excel report generation
• Source control (Git)