Payment Engineer

Application Developer

Location: Tulsa, Oklahoma Work Model: Onsite

Responsibilities

• Provide application support and maintenance for mobile payment platforms, ensuring system uptime and performance.
• Troubleshoot and resolve production incidents, including payment processing issues, API failures, and transaction discrepancies.
• Develop, enhance, and maintain applications using C# / .NET technologies.
• Write and optimize SQL Server queries, stored procedures, and database performance tuning.
• Collaborate with cross-functional teams (engineering, product, security, and operations) to deliver high-quality solutions.
• Support integrations with third-party payment providers and financial services APIs.
• Monitor system health, logs, and transaction flows to proactively identify and resolve issues.
• Participate in on-call rotations and provide timely response to critical production events.
• Assist in cloud migration and hybrid architecture support, working across on-prem and cloud environments (Azure, AWS, or similar).
• Implement and follow secure coding and compliance standards relevant to financial transactions (PCI, data protection, etc.).
• Contribute to continuous improvement initiatives, including automation, monitoring, and performance optimization.

Requirements

• Bachelor's degree in Computer Science, Information Technology, or related field (or equivalent experience).
• 3+ years of experience in application development and support roles.
• Strong proficiency in: C# /.NET Framework /.NET Core, Microsoft SQL Server (query design, performance tuning, stored procedures).
• Experience supporting financial systems or mobile payment platforms (e.g., Cash App, Venmo, Apple Pay, Zelle, or similar).
• Hands-on experience with hybrid environments (on-premises + cloud).
• Familiarity with REST APIs, microservices architecture, and integration patterns.
• Experience with incident management, root cause analysis, and production support processes.
• Understanding of secure development practices and financial data handling.
• Experience with cloud platforms such as Azure or AWS (Preferred).
• Knowledge of payment processing flows, digital wallets, or fintech systems (Preferred).
• Familiarity with monitoring tools (Splunk, App Insights, Dynatrace, etc.) (Preferred).
• Experience with DevOps practices, CI/CD pipelines, and automation tools (Preferred).
• Exposure to containerization (Docker/Kubernetes) (Preferred).
• Strong troubleshooting and problem-solving skills in high-pressure environments.
• Excellent communication and collaboration skills.
• Proactive mindset with focus on system reliability and improvement.

System One, and its subsidiaries including Joulé and Mountain Ltd., are leaders in delivering outsourced services and workforce solutions across North America. We help clients get work done more efficiently and economically, without compromising quality. System One not only serves as a valued partner for our clients, but we offer eligible employees health and welfare benefits coverage options including medical, dental, vision, spending accounts, life insurance, voluntary plans, as well as participation in a 401(k) plan.

System One is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, age, national origin, disability, family care or medical leave status, genetic information, veteran status, marital status, or any other characteristic protected by applicable federal, state, or local law.