Senior Software Engineer | C# .NET | Hybrid Belfast
Senior backend engineering role on a mission‑critical, high‑throughput payments platform.
* C# / .NET, SQL Server, CI/CD, BDD – serious technical challenge at real transaction volumes
* Hybrid working, 2 days in the Belfast city centre office
* Salary Competitive
About the Company
Our client is a globally operating Fintech business who operates across more than 175 countries. Their Belfast engineering team builds and owns infrastructure that simply cannot go down, and has the culture, discipline and technical standards to ensure it does not. The scale is international, the ownership is real, and the engineering is the kind that keeps strong developers engaged for years.
The Role
As a Senior Software Engineer, you will contribute to roadmap delivery, backend service design and the ongoing improvement of a complex, high‑scale system. Working alongside experienced engineers and product partners in an Agile environment, you will have genuine input into technical decisions and real responsibility for what you ship.
Key Responsibilities
* Design and implement roadmap features to a high standard within a collaborative, experienced engineering team
* Build reliable, scalable backend services in C# / .NET, contributing to frontend components where required
* Participate in technical design discussions and contribute meaningfully to architectural decisions
* Ensure all deliverables are well‑tested, technically accurate and delivered on time with strong CI/CD discipline
* Improve development processes, tooling and engineering methodology through hands‑on contribution
* Support software deployment activities across internal test and production environments
* Mentor junior engineers through code reviews, pairing and knowledge sharing
* Investigate production issues, synthesise information across multiple sources and deliver clear, actionable solutions
* Contribute to estimation, planning and transparent communication of progress and blockers
Essential
* 4+ years of commercial software development experience
* Strong server-side development experience in C# / .NET on Windows
* Experience designing and building scalable web service solutions
* Strong relational database experience, SQL Server preferred
* Proven test automation experience including unit testing and BDD frameworks
* Familiarity with CI/CD pipelines (Bamboo, Jenkins, GitLab or similar)
* Solid understanding of design patterns, object-oriented design and refactoring principles
* Experience working in Agile, Scrum or Lean/Kanban environments
* Right to work in the UK on a permanent, full-time basis
* Based in, or within one hour commute of, Belfast
Desirable
* Knowledge of PCI standards
* Experience in high‑availability or high‑throughput engineering environments
* Background in information security or system architecture at scale
Why Apply?
* Genuine career progression within a globally recognised organisation, with clear paths to staff and architectural levels
* Be part of something genuinely big: a platform processing millions of transactions daily across more than 175 countries
* Hybrid working with 2 days in a brand‑new Belfast city centre office
* Increasing Annual leave with length of service, plus bank holidays
* Medical and dental insurance, life cover, income protection and critical illness cover
* Stock purchase plan, cycle to work and electric car scheme
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