Principal Software Engineer | .NET, Payments Platform Location: Belfast Type: Permanent About the Opportunity: This role sits within a Belfast-based engineering group responsible for a high-throughput payments gateway handling millions of card transactions daily. The platform supports customers ranging from small businesses to enterprise-scale venues, where resilience, performance, and uptime are critical. As a Principal Software Engineer, you will act as a senior technical leader within the team, shaping delivery across complex initiatives while remaining hands-on. You will guide engineers of varying levels, influence technical direction, and ensure systems meet high standards for security, scalability, and reliability. What Youll Be Doing: Acting as a senior technical authority within the team, guiding solution design and implementation Leading delivery of complex features and initiatives across the payments platform Designing, modifying, and reviewing complex .NET code with a strong focus on quality and maintainability Advising on testing strategies, validation requirements, and corrective actions Applying deep understanding of engineering standards, methodologies, and PCI security requirements Estimating complex workstreams and contributing to roadmap planning Supporting deployment activities across test and production environments Identifying technical risks, investigating issues, and driving clear resolution paths Improving team effectiveness through better communication, tooling, and engineering practices Coaching and developing engineers through mentoring and hands-on support What Youll Bring: Significant commercial experience building server-side systems using .NET and C# Strong experience designing and delivering scalable web service solutions Solid background working with relational databases such as SQL Server Experience operating within CI/CD environments using tools such as Jenkins, GitLab, or similar Proven experience implementing automated testing practices, including unit and BDD-style tests Strong understanding of object-oriented design, refactoring, and design patterns Deep grasp of core software design principles including modularity, encapsulation, and separation of concerns Experience working in Agile, Scrum, Lean, or Kanban environments Strong analytical and problem-solving skills Clear communication skills and the ability to lead through influence rather than hierarchy Nice to Have: Experience working with payment processing systems or PCI-regulated environments Exposure to software architecture or systems design responsibilities Familiarity with front-end technologies such as HTML and CSS Why Join: Work on high-scale, always-on systems where engineering quality directly impacts customers Principal-level role with real technical ownership and influence Stable platform environment with complex and meaningful engineering challenges Flexible working model with a strong Belfast engineering presence If you're interested or have any further questions on the role, please feel free to reach out to Eve Geddis directly on LinkedIn. Skills: .Net Benefits: Pension Fund Medical Aid / Health Care Work From Home