.NET / C# Architect - Capital Markets | Inside IR35 | Hybrid (3 Days in London)

A leading financial institution is seeking a highly experienced .NET Architect to drive the technical design and implementation of a next-generation Treasury platform. This is a key role responsible for shaping system architecture, guiding development teams, and ensuring the scalability, robustness, and performance of mission-critical trading and treasury systems.

Key Requirements:

• INSIDE IR35
• Hybrid working: 3 days onsite in London
• Must have Capital Markets or Treasury experience

Responsibilities:

• Define and lead the end-to-end architecture for the Treasury platform using modern .NET technologies and distributed systems design.
• Collaborate with business stakeholders, product owners, and senior developers to translate business needs into scalable, high-performance technical solutions.
• Promote engineering best practices, including design patterns, microservices, security, performance optimization, and cloud deployment.
• Lead the design and delivery of integrations with upstream and downstream systems such as Order Management Systems (OMS), Execution Management Systems (EMS), pricing engines, and compliance modules.
• Conduct architecture and code reviews, ensuring alignment with enterprise standards and industry best practices.
• Mentor development teams and help drive delivery within an Agile framework.

Essential Skills & Experience:

• Proven background in .NET architecture roles within capital markets, investment banking, or other financial services environments.
• Deep expertise in C#/.NET Framework and .NET Core, including microservices, multithreaded programming, and real-time distributed systems.
• Strong understanding of treasury operations, fixed income, FX, and derivatives workflows.
• Solid experience with SQL Server, messaging systems (e.g., RabbitMQ, Service Bus), and API development (REST, FIX).
• Experience in cloud-native architecture, ideally with Microsoft Azure (Functions, Logic Apps, Cosmos DB, Blob Storage, Service Bus).
• Familiarity with Order Management Systems such as ThinkFolio, Aladdin, Portware, or Fidessa.
• Knowledge of implementing regulatory and compliance frameworks (e.g., MiFID II, UMR, BCBS).
• Excellent communication skills with the ability to engage both technical teams and business users.
• Exposure to DevOps practices including CI/CD pipelines and Infrastructure as Code (IaC).
• Experience modernizing legacy trading platforms or delivering greenfield systems within capital markets.