Senior Software Engineer (Remote, CA/UK)

Job Overview

NMI is a leading provider of payment gateway solutions, specialising in card‑present solutions and payment processing. Our innovative technologies empower businesses to securely accept payments and optimise transaction processing. With a focus on reliability, security, and innovation, we continuously push the boundaries of what’s possible in the payments industry.

We are seeking an experienced Senior Software Engineer to join our Core Gateway team. The Core Gateway team is responsible for the development, maintenance, and evolution of NMI’s primary payment gateway platforms, powering high‑volume, business‑critical transaction processing for merchants globally.

This team plays a pivotal role in ensuring our gateways operate reliably, securely, and at scale. By continuously improving performance, resilience, and functionality, the Core Gateway team enables seamless payment operations and supports our customers in an increasingly digital economy.

Ideal Candidate

The ideal candidate is a highly skilled software engineer with senior‑level technical depth, strong system design experience, and curiosity to work across components when needed.

Key Responsibilities

• Design and deliver complex backend systems that power secure, scalable, and high‑performance payment processing.
• Take ownership of significant components or services within the Core Gateway platform, ensuring long‑term maintainability and operational excellence.
• Clearly articulate complex technical solutions and trade‑offs to engineers, Product, and stakeholders.
• Guide project delivery within the team, helping break down work, manage technical risk, and ensure high‑quality outcomes.
• Proactively identify and resolve architectural gaps, performance bottlenecks, and reliability risks.
• Lead and participate in design reviews, raising the quality bar across the team.
• Drive improvements in observability, fault tolerance, and operational readiness across services.
• Mentor junior and mid‑level engineers, providing constructive feedback and supporting their technical growth.
• Contribute to the evolution of CI/CD pipelines, testing strategies, and deployment automation.
• Ensure adherence to strong security and compliance standards (e.g., PCI, OWASP, SOC2).
• Participate in the team’s out‑of‑hours on‑call rota, contributing to incident response, root cause analysis, and preventative improvements (typically after a 6‑month onboarding period, with additional compensation provided).

Skills & Experience

• 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 PHP, 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.
• Experience with logging systems (e.g., Logz.io) and optimizing logs preferred.
• Experience with monitoring and alerting systems (e.g., DataDog, NewRelic) preferred.
• Experience designing and building scalable, performant, and reliable systems, and improving reliability in existing systems.
• Deep knowledge of design patterns and their practical application.
• Proven ability to work independently while also fostering teamwork and cross‑team collaboration.
• Proven ability to mentor others and contribute to a strong team culture.
• Strong problem‑solving skills, with the ability to anticipate potential issues and proactively address them.
• Excellent communication skills, capable of explaining complex technical concepts to both technical and non‑technical stakeholders.

Benefits

• Annual bonus scheme dependent on individual and company performance
• Annual salary of £50,000 – £65,000
• 25 days holiday each year (+ bank holidays + 1 day after each year of service with a maximum of 30 days)
• Workplace pension scheme
• Private medical insurance (upon 30 days of employment)
• 7 hours per day, 35 hours per week
• Remote‑first culture
• Great work‑life balance with our Flexi‑time policy
• Family‑friendly policies (Enhanced Maternity and Paternity Pay and Shared Parental Leave)
• Chance to develop with an allocated company training budget
• Bike2Work scheme
• Lifeworks, an Employee Assistance Programme which offers wellbeing, family and financial support services, including 1:1 counseling sessions and discounts on gyms, restaurants, high‑street retailers, and cinema tickets
• Strong commitment to employee wellbeing including mental health first aiders
• Employee referral scheme with generous financial reward
• Bonusly colleague reward scheme

Equal Opportunity Statement

We are an Equal Opportunities employer and will provide reasonable support throughout the recruitment process to applicants who have a disability. Please let us know in advance so that any support, aids or adaptations can be put in place to assist you.

Other Conditions

Please be aware that all offers of employment are made subject to receipt of satisfactory background and financial checks.

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