Principal Software Engineer - C#

Salary: £70,000 - 82,000 per year

Requirements:

• 10+ years of experience in Financial Services building complex front-office trading systems, with demonstrated technical leadership through multi-year delivery
• Proven success leading engineering teams through complex, multi-year transformation programmes
• Hands-on experience across the full software development lifecycle
• Practical experience using AI tools across the development lifecycle, including review discipline for AI-generated code
• Excellent written and verbal communication skills in a matrixed, global organisation
• Self-motivated and proactive approach
• Degree in Computer Science, Engineering, Mathematics, Physics, or a relevant analytical discipline
• Understanding of relative-value execution, including cash/futures basis, calendar spreads, and curve trades
• Familiarity with futures market structure and US Treasury market structure
• Knowledge of futures clearing and margin systems and Treasury settlement rails
• Experience with execution/order connectivity protocols such as FIX or equivalent in an interdealer, agency, or execution-desk context
• Understanding of 24-hour, multi-region trading operations and timezone-aware processing
• Expert-level C# / .NET (LTS), including ASP.NET Core back-end services
• Experience designing and delivering event-driven, service-oriented back-end systems in a production trading environment
• Experience building desktop applications that host web content, such as Electron, Tauri, or custom .NET host
• Comfort with WebSocket bridges, local service APIs, or IPC mechanisms
• Sufficient front-end literacy in React, TypeScript, and Node to make architectural decisions and review code
• Demonstrated ability to leverage coding agents in spec-driven development workflows
• Strong grasp of process isolation, information security, and identity/access management
• Experience with event-driven messaging and least-privilege service boundaries
• Familiarity with modern build pipelines and tools
• Experience designing within formal governance and architecture-review frameworks
• Experience with desktop interop frameworks and protocols such as FDC3, OpenFin, or custom IPC/message-bus implementations is desirable
• WPF or other rich-client .NET UI experience is desirable
• Experience interfacing with third-party desktop APIs such as Bloomberg DAPI is desirable
• Performance engineering experience, including profiling and enforcing hard latency budgets is desirable
• Experience with high-throughput trade and market-data processing at scale is desirable
• Cloud platform experience, such as AWS or equivalent, and experience with containerisation and orchestration is desirable
• Experience with relational data and canonical/JSON data contract design is desirable
• Experience with design-system principles and component-library development is desirable

Responsibilities:

• Act as the primary hands-on technical leader by architecting the platform, writing correctness-critical code, and setting the engineering bar through our own output
• Own the technical direction of the greenfield project, developing high-performance, scalable, and robust solutions from first principles through to production operation
• Design for hard non-functional requirements, including latency and responsiveness budgets, crash containment, and least-privilege isolation between sub-applications
• Work effectively within a matrix management structure, taking designs through group-wide governance while delivering business value and adhering to technology standards and mandates
• Mentor and coach other team members to support performance and career growth
• Work effectively with offshore staffing vendors
• Establish AI-assisted development as a disciplined team practice using company-wide tooling, workflow integration, and rigorous review practices
• Communicate technical trade-offs clearly to trading, compliance, infrastructure, and middle-office stakeholders
• Manage risk and escalate honestly
• Identify and drive refactoring toward the target architecture as the platform grows

Technologies:

• AI
• ASP.NET
• AWS
• C#
• Cloud
• Electron
• Support
• JSON
• Matrix
• Network
• Rails
• React
• Security
• TypeScript
• WPF
• Web
• UX UI Design
• NodeJS
• API
• Architect

More:

We are TP ICAP Group, a world-leading provider of market infrastructure, connecting clients to global financial and commodities markets through responsible and innovative liquidity and data solutions. Our business is home to premium brands and we are the largest interdealer broker in the world by revenue, the number one Energy & Commodities broker, and a leading provider of OTC data and all-to-all trading platforms. Founded in London in 1866, we operate from more than 60 offices across 27 countries and are 5,200 people strong. This role sits within ICAP Relative Value (ICRV), our dedicated global execution division specializing in US Treasuries, Futures, and Options, operating around the clock with a team that executes complex synthetic strategies for institutional clients. The position is based in London at 135 Bishopsgate and is offered as a full-time, hybrid role. We also foster an inclusive culture through TP ICAP Accord, our employee network, and encourage candidates to apply even if they do not meet every criterion.

last updated 34 week of 2026