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 You’ll Be Doing:
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Acting as a senior technical authority within the team, guiding solution design and implementation
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Leading delivery of complex features and initiatives across the payments platform
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Designing, modifying, and reviewing complex .NET code with a strong focus on quality and maintainability
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Advising on testing strategies, validation requirements, and corrective actions
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Applying deep understanding of engineering standards, methodologies, and PCI security requirements
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Estimating complex workstreams and contributing to roadmap planning
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Supporting deployment activities across test and production environments
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Identifying technical risks, investigating issues, and driving clear resolution paths
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Improving team effectiveness through better communication, tooling, and engineering practices
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Coaching and developing engineers through mentoring and hands-on support
What You’ll Bring:
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Significant commercial experience building server-side systems using .NET and C#
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Strong experience designing and delivering scalable web service solutions
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Solid background working with relational databases such as SQL Server
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Experience operating within CI/CD environments using tools such as Jenkins, GitLab, or similar
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Proven experience implementing automated testing practices, including unit and BDD-style tests
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Strong understanding of object-oriented design, refactoring, and design patterns
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Deep grasp of core software design principles including modularity, encapsulation, and separation of concerns
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Experience working in Agile, Scrum, Lean, or Kanban environments
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Strong analytical and problem-solving skills
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Clear communication skills and the ability to lead through influence rather than hierarchy
Nice to Have:
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Experience working with payment processing systems or PCI-regulated environments
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Exposure to software architecture or systems design responsibilities
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Familiarity with front-end technologies such as HTML and CSS
Why Join:
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Work on high-scale, always-on systems where engineering quality directly impacts customers
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Principal-level role with real technical ownership and influence
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Stable platform environment with complex and meaningful engineering challenges
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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.
