Senior Software Engineer

NMI; United States; Remote; USD 115,000 - 130,000; Full time

Benefits offered by this job

Remote first culture

Competitive compensation

Growth opportunities

Flex PTO & sick time

Health, Dental and Vision Insurance

Life and Disability insurance

401k matching

Flexible Spending Account

Employee referral program

Bonusly recognition

Job summary

NMI seeks a Senior Software Engineer to join our Development team, reporting to the Engineering Manager. You will design, build, and maintain core billing systems using C# and PHP, with AI-assisted development through Claude and Cursor.

You will own architectural decisions, mentor teammates, and drive CI/CD improvements while scaling systems for billions of transactions. This remote-first US-based role offers competitive pay and comprehensive benefits.

Qualifications

• 5+ years of experience developing complex software applications in an agile environment.
• Strong proficiency in C# and/or PHP with OO design knowledge.
• Experience building scalable billing/invoicing systems and securing data.

Responsibilities

• Design, develop, and maintain core billing and invoicing systems using C# and PHP.
• Lead technical discussions and drive best practices for maintainability and performance.
• Mentor junior engineers and coach on safe use of AI tools like Claude and Cursor.
• Improve CI/CD pipelines and monitoring to ensure reliable deployments.
• Optimize database queries and system architecture for growth and security.

Skills

C# proficiency or PHP

OO design

Database design

Security best practices

Mentoring

Cross-team collaboration

Education

Bachelor's degree in Computer Science

Tools

Claude

Cursor

Kubernetes

Docker

DataDog

Job description

NMI is looking for a passionate Senior Software Engineer to join our Development team as a result of NMI's continued growth and investment in the underlying systems. This role reports to the Engineering Manager.

As a senior developer with strong experience in C# and/or PHP, you will join a team of industry-leading experts that are talented, ambitious and want to drive the continued development of our payment processing services. Our developers are responsible for software services and deliverables that support the processing of billions of transactions for hundreds of thousands of merchants every year. These applications have to be efficient, reliable, redundant, secure, highly-available and scalable. A background in the development of accounting or billing systems is preferred for this specific role.

AI-assisted development is core to how we build at NMI. Our engineers work with Claude and Cursor every day, and we expect you to use them fluently: to move faster, to raise quality, and to spend more of your time on the problems that need human judgement.

About NMI

NMI, a global leader in payment technologies, allows software and sales professionals to deliver payment innovations to their clients without having to build payment expertise in house. 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 realizing it. We're the platform that powers success for innovative tech created by SMBs, entrepreneurs and fintech startups. 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 democratize the latest payments technology so that everyone can realize the benefits of easy payments across the full spectrum of commerce. Our mission is to use our expertise to enable more payments, in more ways and more places. We provide ISOs, Fintech Innovators and Technologists the freedom to focus on what they do best, liberating them from restricted payment solutions and giving them access to the latest payment technology now and in the future.

How We Work - Our Core Values

• Be a Good Person, It's Simple. We treat everyone fairly and with respect. We lead with kindness, humility and integrity. We take the time to understand each other and our customers. And we serve with care, because customers are never a transaction, and always our focus
• Align, Trust & Go. We debate openly, listen carefully and challenge thoughtfully. Once we decide, we move forward together - holding ourselves accountable to our commitments, and focusing on what matters most to our customers. That alignment creates momentum.
• Raise the Bar. Good enough isn't enough. We stay curious, measure everything, stay honest about progress and keep pushing ourselves to think creatively. We drive change, again and again. And leave things better than we found them. When we raise the bar, our customers feel it too.

Key Responsibilities:

• Design, develop, and maintain core billing and invoicing systems using C# and PHP technologies.
• Use AI-assisted development tools, specifically Claude and Cursor, as a core part of your daily engineering workflow across design, implementation, testing, refactoring, and comprehension of large existing codebases.
• Remain fully accountable for everything you ship: review AI-generated code with the same rigor you apply to any other contribution, verifying correctness, security, performance, and maintainability before it reaches production.
• Take ownership of architectural and design decisions for billing system components.
• Lead technical discussions, participate in code reviews, and drive best practices in maintainability and performance.
• Mentor and support the growth of junior team members, including coaching on effective and safe use of AI development tools.
• Lead improvements to CI/CD pipelines and development processes.
• Implement monitoring, logging, and alerting systems to proactively identify and resolve issues.
• Optimize database queries and system architecture to handle growing merchant and transaction volumes.
• Implement robust security measures to protect sensitive payment and merchant data and ensure compliance with PCI DSS standards, including when working with AI development tools.
• 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.
• Identify, assess, and mitigate risks, including security risks, throughout the software development lifecycle.
• Provide feedback and resolutions to escalated support issues.
• Research and evaluate new technologies and methodologies to improve system performance and developer productivity.
• Bachelor's degree in Computer Science or equivalent experience.
• Minimum of 5 years of experience developing complex software applications in a collaborative, agile environment.
• Advanced proficiency in C# and/or PHP, with a strong understanding of object-oriented design principles and design patterns.
• Advanced experience with database design, optimization, and performance tuning.
• Strong knowledge of security and compliance best practices (e.g. OWASP, PCI).
• Excellent communication skills, with a proven ability to mentor others, contribute to a strong team culture, and work with others across teams to move projects forward.
• Experience designing and architecting scalable, distributed systems with consideration for performance, reliability, and maintainability.
• Ability to translate complex business requirements into technical solutions.
• Proven track record of code reviews and maintaining code quality standards.
• Proven ability to understand, debug, and enhance complex existing systems with limited documentation and evolving requirements.
• Hands‑on experience building production software with Claude and Cursor, our standard toolset, and a willingness to make them a daily part of how you work.
• Sound judgment about where AI tooling adds leverage and where it does not, including an understanding of how these tools fail in large, legacy or sparsely documented systems.

Preferred Qualifications:

• Experience with logging systems (such as Logz.io) and optimizing logs.
• Experience with containerization (e.g. Kubernetes, Docker, etc.).
• Experience with monitoring and alerting systems (e.g. DataDog, NewRelic, etc.).
• Experience with CI/CD pipelines, automated testing, and deployment processes.

Do you feel like you have a slightly out of the ordinary career path or history? We are open to all walks of life and very willing to hear your story. Please don't feel like this should be a barrier to securing a great career at NMI! We appreciate success can come in all shapes and sizes.

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

• A remote first culture!
• Competitive compensation and benefits
• Personal growth and advancement opportunities
• Flex PTO & dedicated sick time
• Health, Dental and Vision Insurance
• Life, ADD, Short-term and Long-term Disability insurance
• 401k matching up to 4% after two months of service
• Flexible Spending Account
• Employee referral program
• Bonusly colleague recognition

We believe that having a diverse group of employees strengthens both our work and our workplace. We're focused on making NMI more diverse and welcoming with initiatives like having a dedicated Diversity, Equity & Inclusion action group, diversity goals for hiring, anonymized resume screening, affinity groups such as our Women's network and LGBTQ+ Network, open forums for discussions on diversity and social justice, and measuring inclusion and belonging as part of our regular employee engagement surveys.

NMI is committed to providing equal employment opportunity for all persons regardless of race, color, religion, sex, age, marital status, national origin, sexual orientation or sexual identity, genetic information, citizen status (except those that do not have the legal right to be employed in the United States), disability, military service, service member, veteran status, or any other basis protected by applicable law.

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

Salary range, depending on experience:

$115,000 - $130,000 USD