C# / .NET Developer – Front Office Liquidity, Treasury & Risk Systems

MARGO is a tech-native consultancy delivering high value-added IT expertise to the financial services industry. We specialise in complex software engineering environments where performance, robustness, and scalability are critical: real-time systems, distributed architectures, high-throughput engines, and complex financial calculations. Joining MARGO means working in demanding Front Office, Global Markets, and Treasury IT environments while benefiting from a human-sized structure, dedicated technical support, and tailored career development paths.

You will join the Front Office / Treasury IT environment  of a premier Tier-1 investment bank in London.

Working within the Non-Linear IT team across distributed locations, you will engineer mission-critical systems supporting Liquidity Risk, Treasury ALM, XVA, and Financial Resource Management. The platform operates in direct proximity to trading desks, Treasury, and risk managers to calculate balance-sheet funding costs and risk exposures in real time.

The team is actively executing an advanced migration toward a modern, event-driven back-end microservices architecture while supporting interactive UI tools used daily by several hundred users.

We are looking for a passionate Senior C# / .NET Developer to build, modernize, and scale our core front-office calculation engines.

This is a 100% hands-on Individual Contributor seat. You will write clean, high-performance back-end code and translate complex financial logic directly into production systems without business analyst or translation layers.

• Design, build, and optimize high-performance back-end calculation engines using modern C# .NET.

• Develop asynchronous, message-driven microservices (using Rebus / messaging queues) and Windows Services for distributed processing.

• Build and tune database objects, complex queries, and data access layers using MS SQL Server and Dapper.

• Implement real-time communication feeds and RESTful APIs using ASP.NET Web API and SignalR.

• Leverage LLMs and practical agentic AI workflows (Copilot, Claude) within daily engineering to accelerate testing, refactoring, and delivery.

Implement core calculation logic across at least two of the following business areas:

• Deliver clean, testable, and maintainable code adhering to SOLID principles and design patterns.

• Participate in automated CI/CD pipelines using Git (Bitbucket), TeamCity, Jenkins, or Ansible.

• Maintain high standards of ownership, transparency, and operational risk mitigation.

• Front-end web development with React, Redux, TypeScript, and HTML

• Proven experience as a Senior C# .NET Developer in demanding, performance-sensitive banking environments.

• Deep understanding of Object-Oriented design patterns, asynchronous programming, and multithreading.

• Solid back-end experience building event-driven services, messaging systems, and Windows Services.

• Strong MS SQL Server database expertise and experience with lightweight ORMs (Dapper).

• Practical familiarity with enterprise DevOps pipelines and AI developer tools (Copilot/Claude).

• A dedicated individual contributor mindset committed to daily hands-on coding.