c# developer, banking, £750 Outside IR35, Remote, London at CipherTek Recruitment, London, 12 Months, £Contract Rate

Role: Expert .NET Developer - Cross Asset Trading System

Location: Very Flexible. Can offer Remote with occasional travel to London City offices

Contract: 12 months

Rate: Up to £750/day (OUTSIDE IR35)

About the Role:

We are partnering with a leading investment bank on an ambitious programme to modernise and enhance their cross-asset trading systems. This is a technically challenging, hands-on role, ideal for an expert .NET developer with a strong SQL Server background and experience working in financial environments.

Please note, you MUST have very strong low level C#, able to work through complex multithreaed performance issues. Good understanding of multi-threading, garbage collection, concurrency, the CLR is very important for this role.

You will be joining a highly skilled team focused on performance, reliability, and scalability, tackling complex issues in Real Time, data-driven applications. This is purely a tech-heavy role-business knowledge is helpful but not required.

What You'll Be Doing:

• Design, develop, and maintain RESTful APIs using .NET technologies (C#, ASP.NET Core).
• Redesigning and refactoring high-activity tables to improve performance and maintainability
• Developing frameworks and tooling for Real Time monitoring of trading systems
• Modernising and upgrading Legacy codebases, driving best practices in .NET development

What We're Looking For:

• Expert .NET Developer: Deep knowledge
• SQL Server Proficiency: Strong fundamentals in querying, table design, and ETL processing large datasets (performance tuning not required)
• ADO.NET Expertise: Familiarity with EntityFramework or other ORMs is a plus, but not essential
• Async & Multithreading Mastery: Experience in Real Time, data-driven applications
• Design and build scalable, high-performance Back End services using .NET9.
• Familiarity with containerization and orchestration (Docker, Kubernetes) is a plus.
• Experience with CI/CD pipelines and automated testing frameworks.
• Attention to Detail: Ability to spot rare, critical issues before they reach production
• Previous experience in the finance industry, ideally in trading systems

Why This Role Is Exciting:

• Work remotely while tackling cutting-edge technical challenges
• Collaborate with a high-performing team on a strategic, high-impact programme
• Influence system design, architecture, and long-term performance improvements
• Competitive daily rates up to £750

If you're a highly skilled .NET developer who thrives in challenging, high-stakes environments and loves working with complex, Real Time systems, this is the perfect opportunity to make an impact.