Senior Software Engineer - Remote

Overview

NMI is excited to add a Senior Software Engineer to our growing team in the UK. This role sits within the Protocols team—responsible for building and maintaining mission-critical services that connect to card payment acquirers and processors. These systems, written primarily in C#, must be scalable, secure, observable, and highly available, ensuring seamless transaction processing for our global customer base.

In Short

• Contribute to the architecture of highly observable and fault-tolerant systems.
• Lead technical discussions, participate in code reviews, and drive best practices in maintainability and performance.
• Actively mentor and support the growth of junior team members.
• Collaborate with cross-functional teams, including Product and QA, to ensure high-quality delivery.
• Contribute to the evolution of our CI/CD pipelines and observability tooling.
• Participate in the out-of-hours on-call rota to respond to incidents impacting payment flow.

Requirements

• Bachelor's degree in Computer Science, Information Technology, or equivalent experience.
• Minimum of 5 years of experience developing complex software applications in a commercial environment.
• Advanced proficiency in C# (preferred) or Java, with strong understanding of object-oriented design principles.
• Deep understanding of the full software development lifecycle (SDLC) and agile methodologies.
• Experience with relational databases (e.g., MySQL, SQL Server, Oracle).
• Strong knowledge of security best practices (e.g. OWASP, PCI, SOC2, HIPAA).
• Proficiency with Google Cloud Platform (GCP), Amazon Web Services (AWS), or similar cloud environments.
• Demonstrated experience applying modern software development practices in a collaborative, agile environment.
• Excellent communication skills, with a proven ability to mentor others and contribute to a strong team culture.
• Experience with logging systems (such as Logz.io) and optimizing logs preferred.
• Experience with containerization (e.g. Kubernetes, Docker, etc.) preferred.
• Experience with monitoring and alerting systems (e.g. DataDog, NewRelic, etc.) preferred.

Benefits

• Annual bonus scheme dependent on individual and company performance.
• Annual salary of £47,000 - £57,000.
• 25 days holiday each year (+ bank holidays + 1 day after each year of service with up to a max. of 30 days).
• Workplace pension scheme.
• Private medical insurance (upon 30 days of employment).
• 7 hours per day, 35 hours per week.
• A remote first culture.
• Great work-life balance with our Flexi-time policy.
• Family Friendly policies (Enhanced Maternity and Paternity Pay and Shared Parental Leave).
• A chance to develop with an allocated company training budget.
• Bike2Work Scheme.
• Lifeworks, an Employee Assistance Programme which offers wellbeing, family and financial support services, such as assessments, resources and even 1:1 counselling sessions. It also offers interesting perks such as discounts on gyms, restaurants, high street retailers and cinema tickets.
• A strong commitment to employee wellbeing including mental health first aiders.
• Employee referral scheme with generous financial reward.
• Bonusly colleague reward scheme.