Salary: £30,000 - 60,000 per year Requirements: 8 years backend software engineering Proven experience designing distributed, secure systems Experience operating in regulated or compliance-heavy environments Strong C# / .NET backend expertise Deep understanding of high-volume transactional databases Strong understanding of authentication and secure session design Experience designing for high availability and fault tolerance Strong production troubleshooting capability Responsibilities: Own and evolve a high-throughput, security-critical payment gateway platform Define and evolve gateway architecture across multiple services Lead design of secure, high-availability transaction systems Drive decisions across authentication, transaction routing, and merchant services Identify and reduce systemic technical debt Champion alignment with PCI DSS 4.0 requirements Lead threat modelling and secure design reviews Drive vulnerability remediation strategy and prioritisation Define expectations for TDD / BDD and automated test coverage Establish CI/CD quality gates and release confidence standards Act as an escalation point for complex architectural decisions Mentor Senior Engineers and grow technical leadership capability Technologies: Backend C# CI/CD Security TDD ASP.NET OWASP More: We are a leading technology firm based in Belfast, offering a hybrid work environment that promotes flexibility and collaboration. Our mission is to own and evolve a high-throughput payment gateway platform vital for secure financial transactions. We prioritize our teams growth and development, providing opportunities for mentorship and technical leadership, along with competitive benefits to ensure a rewarding work experience. last updated 11 week of 2026