Senior C# / .NET Developer
MARGO
Senior C# / .NET Developer
MARGO
SME-focused bank offering credit management tools
Join MARGO in the UK (London) – Perm & Contracting Opportunities
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 & Engineering
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.
Functional Implementation
Implement core calculation logic across at least two of the following business areas:
Liquidity Risk & Treasury: Cash-flow time-bucketing, NSFR, RNFB, LCR, or liquidity buffers.
Cash Forecasting: Forward cash projections and contractual vs. behavioral maturities.
Balance Sheet & Capital Metrics: Leverage exposure and financial resource utilization.
XVA & Pricing Adjustments: CVA, FVA, ColVA, and funding costs.
Risks & Greeks: Non-linear sensitivities (Delta, Gamma, Vega) and PnL Explain.
Financial Products: Listed or OTC derivatives.
Pre-Trade Analytics: Trade simulation, margin/funding impact checks, and booking workflows.
Delivery & Engineering Standards
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.
Core Technologies
Languages & Frameworks: C# .NET, Windows Services, ASP.NET Web API, SignalR
Architecture & Messaging: Event-driven architecture, asynchronous message-driven systems (Rebus), Service-Oriented Architecture (SOA)
Data & Storage: MS SQL Server (performance tuning, schema design), Dapper
DevOps & CI/CD: Git, TeamCity, Jenkins, Ansible
Modern Tooling: Practical experience applying LLMs / agentic AI tools in software engineering
Valued / Nice-to-Have
Front-end web development with React, Redux, TypeScript, and HTML
Essential
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.
Why Join MARGO
·Access to multi-asset Front Office, Trading and Electronic Trading environments
·Highly technical and challenging engineering assignments
·Clear positioning between HFT and non-HFT trading systems
·Strong emphasis on skill development and long-term career progression
·Human-sized consultancy with close support and high-quality missions
Interested? Motivated? Apply on our website or at [email protected]
MARGO is a banking partner for small and medium-sized businesses. It provides loans and tools to manage company cash flow. How it works: SMEs access credit options and a digital cash-management platform to handle payments, receipts, and liquidity. The bank focuses on helping leaders grow by offering financing and treasury tools that fit small and mid-sized operations. How it stands out: It is an independent bank dedicated to SMEs, offering tailored financing and cash-management services rather than broad services for all customers, which helps smaller companies manage money more effectively. Goal: To help SME leaders grow their businesses by providing affordable credit and practical cash-management tools.
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