Senior C# Developer

Reggie & Cole; Greater London; Hybrid; GBP 90,000 - 120,000; Full time

Benefits offered by this job

Pension up to 17%

Annual Bonus

34 days holiday + flexible benefits

Job summary

Reggie & Cole in London is hiring a Senior C# Developer to take hands-on technical ownership inside one of its core platform teams. The platform is cloud-based, .NET throughout, and supports secure services for end users, internal case management, client reporting, and live integrations out to third-party financial systems.

The role focuses on design, refactoring, and performance improvements, mentoring others, and shaping the platform's growth.

Qualifications

• Deep commercial C# on a .NET codebase you know well.
• Ownership of live software: releases, incidents, fixes.
• Performance work across C# and data layer with EF/EF Core and SQL Server/Azure SQL.
• API and service design that survives real load in ASP.NET/ASP.NET Core.

Responsibilities

• Significant slices of the platform from design to release notes.
• Make architecture and refactoring decisions for future growth.
• Lead data layer scaling and external integrations.
• Implement monitoring, logging and alerting around what you build.
• Own release processes and post-release behavior.
• Contribute to code reviews and mentoring across the team.
• Apply AI-assisted tooling while owning the shipped output.
• Support secure development in sensitive data environments.

Skills

C#

.NET

ASP.NET Core

Azure

EF Core

SQL Server

Code review

CI/CD

Testing

Security

Tools

Entity Framework

SQL Server

Azure SQL

Azure Functions

ASP.NET Core

Job description

Senior C# Developer / Senior Software Engineer

Working pattern: Hybrid. x3 days in Office

Location: London

Benefits: Pension up to 17%, Bonus, 34 days holiday + a heap of flexible benefits.

A global business is hiring a Senior C# Developer to take hands-on technical ownership inside one of its core platform teams.

The platform is cloud-based, .NET throughout, and carries real weight: secure services for end users, internal case management, client reporting, and live integrations out to third-party financial systems. It is growing, and they want someone senior enough to shape how it grows rather than just add to it.

What you would be running:

• Significant slices of the platform, yours from the first design conversation through to the release note and whatever comes back afterwards.
• The judgement call on technical debt in a mature C# codebase: what is genuinely holding the platform back, what is cosmetic, and what the team should spend its next quarter on.
• Larger refactoring and re-architecture work when the answer is that the current shape will not carry where the product is going.
• The data layer as the platform scales, including the integrations that reach outside it.
• Whether problems surface on your terms or the user's, through the monitoring, logging and alerting you put around what you build.
• How releases go out and what happens when one does not behave.
• The engineering standard around you, set through code review, mentoring and the example your own work sets.
• AI-assisted tooling used with your name still on the output, which they have been deliberate about wanting rather than quietly tolerating.

What they need from you:

• Deep commercial C# on a .NET codebase you stayed with long enough to know its history. .NET 8 or later ideally, though what you did with it matters more than the version number.
• Ownership of live software: releases you planned, incidents you investigated, production problems you fixed at 6pm on a Friday.
• Performance work with evidence behind it, across both the C# and the data layer, using Entity Framework or EF Core against SQL Server and Azure SQL.
• API and service design that survived contact with real load, built in ASP.NET or ASP.NET Core.
• Mentoring and code review you have already done, with a view on what makes feedback land rather than just get given.
• Azure in anger: Functions, WebJobs, Blob Storage, and Application Insights when something needs diagnosing.
• CI/CD and automated build and deployment as part of how you work, not something a platform team handles for you.
• Tests you wrote and then had to maintain, which is where most people find out what their testing habits are really worth.
• Secure development practice, in an environment where the data is sensitive and that is not a formality.

Useful but not essential:

regulated environments, a major refactor or migration onto modern .NET, considered use of AI-assisted development tooling where you still own what ships.

our customer is unable to sponsor at this time.