Senior Software Engineer (C#)

Network Merchants Inc.; United Kingdom; On-site; GBP 48,000 - 58,000; Full time

Job summary

A leading payment solutions provider in the United Kingdom seeks an experienced Senior Software Engineer to join their Payments Processing group. The ideal candidate will have a strong background in C# and object-oriented programming principles, along with significant experience developing secure and scalable payment solutions. This role includes technical leadership, mentoring junior engineers, and ensuring best practices in software development and security compliance. Competitive salary package and benefits are offered, promoting work-life balance and employee wellbeing.

Benefits

Annual bonus scheme

Private medical insurance

Employee referral scheme

Bike2Work Scheme

Flexible work hours

Qualifications

• Minimum of 5 years of experience in developing complex software applications.
• Advanced proficiency in C# or Java with strong OOP principles.
• Deep understanding of security best practices and compliance requirements.

Responsibilities

• Design, develop, and implement scalable, high-quality software solutions.
• Lead architectural and design discussions for maintainable software.
• Mentor junior engineers and participate in code reviews.

Skills

C#

Object-oriented programming

Java

SDLC

Agile methodologies

Networking concepts

Security best practices

Education

Bachelor's degree in Computer Science or equivalent

Tools

MySQL

SQL Server

Oracle

Job description

NMI is a leading provider of payment gateway solutions, specializing in card-present solutions and payment processing. Our innovative technologies empower businesses to securely accept payments and optimize transaction processes. 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 Software Engineer to join our Payments Processing group. This group focuses on developing and maintaining world-class payment solutions, including PIN pad and card reader integration and processor/acquirer connectivity.

The ideal candidate:

The ideal candidate will have extensive experience in C# and a strong grasp of object-oriented programming principles. Candidates with expertise in other object-oriented languages (e.g., Java) will also be considered if they have demonstrable experience with a .NET language.

As a Senior Engineer, you will play a leadership role in designing, developing, and maintaining solutions that integrate PIN pads and card readers into Payment Device SDKs for card-based transactions, including contactless, full Chip-and-PIN, magnetic stripe, and manually keyed transactions. You will be expected to take ownership of technical decisions, proactively address challenges, and contribute to the continuous improvement of our CI/CD pipeline.

Your responsibilities will extend beyond implementation, as you will mentor junior engineers, drive technical discussions, and ensure that our solutions meet high standards of security, performance, availability, and reliability.

Key Responsibilities:

• Design, develop, and implement scalable, high-quality software solutions that are secure, reliable, and performant.
• Lead architectural and design discussions, ensuring adherence to best practices and maintainability.
• Write and review high-quality, well-documented code with an emphasis on efficiency and scalability.
• Conduct thorough code reviews, identifying potential errors, inefficiencies, and opportunities for improvement in the codebase.
• Provide technical leadership and mentorship to junior and mid-level engineers, fostering a culture of learning and collaboration.
• Communicate project status, risks, and technical decisions effectively to both technical and non-technical stakeholders.
• Collaborate closely with Product Owners, Developers, and QA teams to ensure successful product releases.
• Proactively identify, assess, and mitigate risks, including security risks, throughout the software development lifecycle.
• Contribute to the evolution of CI/CD pipelines, improving automation and deployment processes.
• Join the team’s out-of-hours on-call rota to support critical product alerts. This typically starts after 6 months of onboarding, and we provide additional compensation to acknowledge the commitment and disruption to your time.

Skills & Experience:

• Bachelor's degree in Computer Science, Information Technology, or equivalent experience.
• Minimum of 5 years of experience in developing complex software applications in a commercial environment.
• Advanced proficiency in C# (preferred) or Java, with a strong understanding of object-oriented design principles and software architecture.
• Deep understanding of the Software Development Life Cycle (SDLC) and agile methodologies.
• Experience with relational databases (e.g., MySQL, SQL Server, Oracle) and optimizing database interactions.
• Strong knowledge of security best practices, including secure coding principles and compliance requirements (e.g., OWASP Top Ten, PCI, SOC2, HIPAA).
• Proficient in networking concepts such as sockets, HTTPS, DNS, and SSL.
• Deep knowledge of design patterns and their practical application.
• Proven ability to work independently while also fostering teamwork and cross-team collaboration.
• Demonstrated ability to mentor junior engineers and contribute to the growth of the engineering team.
• 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.

As well as being a part of something exciting everyday, you will also receive the following benefits:

• Annual bonus scheme dependent on individual and company performance
• Annual salary of £48,000 - £58,000
• 25 days holiday each year (+ bank holidays + 1 day after each year of service with up to a max. of 30 days)
• Private medical insurance (upon 30 days of employment)
• 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

We’re looking for creative and passionate people who share our vision of making payments easy. If that sounds like you and you meet the requirements above, then please click on 'Apply for this job'!

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.

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

About us

NMI enables our partners with choice, and challenges the one‑size‑fits‑all approach to payments. You've probably used NMI in the last 24 hours without even realising it. We’re the platform that powers success for innovative tech created by SMBs, entrepreneurs and fintech start‑ups. We’re creative problem solvers who help visionaries smash through boundaries and think beyond what’s possible so they can think about what’s next. But we’re not just built for the tech savvy. We democratise the latest payments technology so that everyone can realise the benefits of easy payments across the full spectrum of commerce. We’re all about enabling more payments in more ways and more places.

Please note that in compliance with the data protection regulations within your jurisdiction, any personal information submitted with your job application may be collected and used by NMI for the purpose of recruitment and employment‑related activities. By submitting your application, you acknowledge and provide explicit consent to the processing of your personal information as described in our privacy policy found on our website. For more information on how we process your information, please read our privacy policy here:https://www.nmi.com/legal/privacy-policy/

Salary range, depending on experience:

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We’re always looking for passionate life‑long learners to join our growing team. If you think NMI is the right place for you, apply today! If you know someone who would be the right fit, share this opportunity.