Full Stack Engineer | C# .NET + React | Global Trading Firm | London, hybrid

Full Stack Engineer | C# .NET + React | Global Trading Firm | London, hybrid

Our client is a global, privately held trading 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 (C#.NET with React) with a strong mathematical/ quantitative background or strong mathematical mindset, 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 - (60/40 split)

Design performant backend services and APIs that support data-heavy, computation-driven use cases and 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 3 years' of strong commercial experience with C# and .NET, including ASP.NET Core and Web APIs.

At least 2years' 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