An exciting opportunity for an experienced Senior Software Developer to join a highly technical engineering team building sophisticated software used across trading and quantitative research. This is a role for a strong C#/.NET engineer who enjoys solving difficult technical problems, working on performance-critical systems and having genuine input into how software is designed and built. You'll work across both greenfield development and established platforms, creating scalable, reliable and high-performance applications that directly support trading strategies and quantitative research. As a senior engineer, you'll have significant influence over architecture, technical direction and engineering standards, while collaborating closely with quantitative researchers, traders and other experienced technologists. What You'll Be Doing Design and build high-performance applications using C# and modern .NET Take ownership of complex development projects from initial design through to production Influence architecture, technical design and engineering direction Build scalable systems supporting automated trading, quantitative research and data-driven applications Work directly with researchers and traders to turn complex requirements into robust software solutions Design and optimise relational database solutions using SQL Server, Oracle or similar Identify and resolve performance bottlenecks across applications and databases Develop reliable, maintainable and highly scalable software Work with multi-threading, concurrency and asynchronous programming Investigate complex technical challenges and deliver long-term solutions Contribute to code reviews, automated testing, CI and development tooling Mentor other developers and help raise engineering standards across the team What We're Looking For 5+ years' commercial software development experience Strong C# and modern .NET development experience Excellent knowledge of OOP, software design principles and architecture Experience designing and building production-grade, scalable applications Strong SQL experience with SQL Server, Oracle or another relational database Experience developing systems where performance, reliability and scalability matter Strong understanding of the full software development lifecycle Excellent analytical and problem-solving skills Strong communication skills and the ability to work effectively with technical and non-technical stakeholders Degree in Computer Science, Mathematics, Physics, Engineering or another relevant technical discipline Highly Desirable Experience in any of the following would be particularly valuable: Multi-threaded and concurrent application development Asynchronous and parallel programming Low-latency or high-throughput systems TCP/IP, UDP or network programming Distributed systems and service-oriented architectures Performance profiling and optimisation Automated testing and continuous integration Windows development technologies Git and modern development workflows Financial markets, quantitative research or algorithmic trading Working alongside quantitative analysts, researchers, traders or data scientists Why This Role? This is an opportunity to work on technically challenging software where performance and engineering quality genuinely matter. You'll have the freedom to influence architecture and technical decisions, tackle complex engineering problems and see the direct impact of the systems you build in a demanding, data-driven environment. If you're an experienced C#/.NET developer looking for more technical ownership and the opportunity to work on sophisticated trading and research technology, this could be an excellent next move. Spectrum IT Recruitment (South) Limited is acting as an Employment Agency in relation to this vacancy