Senior Software Engineer

NMI is hiring a Senior Software Engineer to develop and maintain billing and invoicing systems that support its payment processing services. The role includes making architectural decisions, improving system reliability, security, and performance, and mentoring team members while using AI-assisted development tools.

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

Requirements:

• 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
• A background in the development of accounting or billing systems is preferred for this specific role
• 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