Senior C# .NET DeveloperMayfair, London - Hybrid (1 - 2 days per week in the office)£68,000 - £72,000 per annumThe RoleOur client is hiring a backend C# .NET Developer to join their engineering team in a hybrid role (1 - 2 days per week in the office). You ll help build and maintain high-performance backend systems that support searching, order processing, and background processes with a strong focus on both application logic and data access.This role is ideal for someone confident in both C#/.NET development and SQL, and who enjoys working on clean, maintainable code and performance-optimised database logic.What You ll Be Working On:Designing and building backend services in C#.Building secure, well-structured APIs with throttling and versioning.Developing durable workflows.Writing efficient and scalable SQL queries, stored procedures, and scripts.Integrating external systems with custom data synchronisation logic.Utilising Open Telemetry and Grafana for logs, metrics, tracing, and alerting across backend services.Contributing to technical design discussions, code reviews, and deployments.What They re Looking For:Strong experience in C#/.NET backend development.Solid understanding of data modelling, indexing, and performance tuning.Skilled in writing and optimising complex SQL queries and stored procedures.Experience building and maintaining APIs, background jobs, and integration points.Attention to detail, clean code, and a performance-first mindset.Great problem-solving an