Full Stack Engineer | C# + React | Global Trading Firm | London

Full Stack Engineer | C# + React | Global Trading Firm | London

Our client is a global, privately held firm, operating in fast-moving, data-intensive markets. Technology is central to how the business runs, with engineers building analytics, optimisation, and decision-support systems used directly by front-office, fiscal, commercial, and operational teams. The environment is high-performance, low-bureaucracy, and focused on solving complex, real-world problems where accuracy, speed, clarity, and commercial impact genuinely matter.

The firm is now looking for a Full Stack Developer with a strong mathematical, analytical, or quantitative background to help build and scale platforms that support complex modelling, forecasting, optimisation, and decision-making workflows.

This role is ideal for someone who enjoys combining serious problem-solving with modern software engineering, working across C#/.NET backend services and React frontends, and who is comfortable working with complex data, models, business logic, constraints, and numerical accuracy.

You do not need to be a quant developer, but you should enjoy working close to mathematical problems, optimisation logic, and business-critical analytical systems.

📍 London City, hybrid working

⌛Permanent Role

💷Highly competitive base + bonus + benefits package

What You’ll Be Doing

• Build and evolve end-to-end analytics and decision-support applications using C#/.NET and React.
• Design performant backend services and APIs that support data-heavy, computation-driven use cases.
• Create clear, intuitive React UIs that expose complex datasets, workflows, scenarios, and modelling outputs.
• Work closely with traders, analysts, fiscal, finance, commercial, and operations teams to translate quantitative and business requirements into production systems.
• Contribute to optimisation-focused tooling, including models involving constraints, scenarios, allocation, forecasting, and decision-support logic.
• Apply strong engineering principles to problems where correctness, performance, and clarity genuinely matter.
• Contribute to system design, architecture discussions, code reviews, and wider technical decisions.

Essential Requirements

• Bachelor’s or Master’s degree in Mathematics, Applied Mathematics, Computer Science, Engineering, Physics, Operations Research, or a similarly quantitative discipline.
• At least 5 years' of strong commercial experience with C# and .NET, including ASP.NET Core and Web APIs.
• At least 4 years' of strong experience with React and modern frontend development, with the ability to build clean, maintainable, data-driven user interfaces.
• Strong mathematical or analytical problem-solving ability, with confidence working around numerical data, models, constraints, edge cases, and correctness.
• Exposure to linear programming, mathematical optimisation, operations research, modelling, forecasting, or decision-support systems.
• Solid understanding of data structures, algorithms, and computational problem-solving.
• Experience working with relational databases and SQL, such as SQL Server, PostgreSQL, or Oracle.
• Ability to work closely with both technical and non-technical stakeholders, including fiscal, finance, commercial, trading, analytical, or operational teams.
• Strong communication skills and a pragmatic engineering mindset.

Nice to Have

• Experience in trading, commodities, financial services, analytics platforms, or commercial optimisation environments.
• Hands-on exposure to optimisation libraries, solvers, or modelling tools.
• Experience with event-driven systems, messaging, async workflows, or concurrent systems.
• Experience building tools used by fiscal, finance, trading, analytics, or commercial teams.
• Interest in linear programming, constraint optimisation, modelling, scenario analysis, or decision-support platforms.

📧If you are interested in this Full Stack Developer Role in London, please apply directly to this advert with your updated CV or email it to chantelle.smith@sourcegroupinternational.com