Senior Software Engineer — O'Fallon, Missouri

Our Purpose Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, we’re helping build a sustainable economy where everyone can prosper. We support a wide range of digital payments choices, making transactions secure, simple, smart and accessible. Our technology and innovation, partnerships and networks combine to deliver a unique set of products and services that help people, businesses and governments realize their greatest potential. Title and Summary Senior Software Engineer This role is part of the Software Engineering team within Mastercard Payment Gateway Services (MPGS) and collaborates with engineers, product teams, and stakeholders across the globe. The team serves as a centralized engineering function that partners with domain teams to build and operate systems at scale by embedding reliability engineering practices, including observability, automation, performance management, and operational excellence, throughout the software development lifecycle. As a Senior Software Engineer, you will develop software while also contributing to reliability, observability, and production support. You will design, build, test, deploy, and support business-critical Mastercard payment gateway applications while providing technical leadership and mentorship within a cross-functional engineering team. Are you an experienced Software Engineer who enjoys building scalable applications and solving complex production issues? Do you thrive in collaborative environments where Software Engineering, QA, and DevOps teams work together to deliver highly reliable solutions? Do you enjoy learning new technologies and helping others grow their technical capabilities? Role • Design, develop, test, deploy, and maintain large-scale Software applications and globally deployed payment gateway products. • Build scalable, secure, and maintainable solutions using Java 17+, Spring Framework, and Spring Boot. • Apply software design and architecture principles to deliver high-quality technical solutions. • Contribute across the full software development lifecycle, from requirements and design through deployment and support. • Develop primarily backend services while contributing to full-stack functionality using modern front-end frameworks such as React, Angular, Vue, or similar technologies. • Create and maintain unit, functional, and integration tests to ensure application quality and reliability. • Perform code reviews and provide technical leadership, design guidance, and mentorship to developers and testers. • Collaborate with engineering, QA, DevOps, and business stakeholders to deliver customer-focused solutions. • Apply secure coding practices and engineering best practices throughout the development lifecycle. • Troubleshoot complex application and system issues, perform root cause analysis, and implement sustainable solutions. • Design and maintain observability solutions using tools such as Dynatrace, Datadog, Splunk, and Grafana. • Improve system performance, scalability, reliability, and operational readiness through monitoring, automation, and performance engineering practices. • Drive CI/CD and automation improvements using Jenkins, Artifactory, and related tooling. • Support applications deployed in public and private cloud environments, including PCF and Kubernetes-based platforms. All About You Required Qualifications • Bachelor's or Master's degree in Computer Science, Engineering, Information Technology, Information Systems, or a related field, or equivalent practical experience. • 5+ years of experience developing and supporting large-scale, distributed software applications. • Advanced Java experience, preferably Java 17+, with strong Spring Framework and Spring Boot expertise. • Experience with software design, architecture, and secure coding practices. • Experience designing and maintaining unit, functional, and integration tests. • Experience with modern front-end frameworks such as React, Angular, Vue, or similar technologies. • Hands-on experience with observability and monitoring tools such as Dynatrace, Datadog, or Splunk. • Experience with CI/CD and automation tools, including Jenkins and Artifactory. • Experience working in public or private cloud environments. • Strong troubleshooting, performance optimization, and problem-solving skills. • Demonstrated ability to provide technical leadership through code reviews, design reviews, mentorship, and knowledge sharing. • Ability to work independently and collaboratively in a cross-functional team environment. Preferred Qualifications • Experience with Docker, Kubernetes, or similar containerization platforms. • Experience with PCF, AWS, Azure or cloud platforms. • Experience with GitHub Actions, Terraform, Ansible, Chef, or Habitat. • Experience with Grafana. • Proficiency in Python or Bash scripting. • Knowledge of OWASP Top 10 and PCI DSS. • Commitment to continuous learning and professional development. Key Technical Skills • Java 17+ • Spring Framework / Spring Boot • Full-Stack Development (React, Angular, Vue, or similar) • Software Design & Architecture • Unit, Functional & Integration Testing • CI/CD & Automation • Jenkins • Artifactory • Observability & Monitoring • Dynatrace • Datadog • Splunk • Grafana • Cloud Platforms (Public & Private Cloud) • PCF • Kubernetes • Performance Engineering • Secure Coding Practices • Troubleshooting & Root Cause Analysis Mastercard is a merit-based, inclusive, equal opportunity employer that considers applicants without regard to gender, gender identity, sexual orientation, race, ethnicity, disabled or veteran status, or any other characteristic protected by law. We hire the most qualified candidate for the role. In the US or Canada, if you require accommodations or assistance to complete the online application process or during the recruitment process, please contact reasonable_accommodation@mastercard.com and identify the type of accommodation or assistance you are requesting. Do not include any medical or health information in this email. The Reasonable Accommodations team will respond to your email promptly. Corporate Security Responsibility All activities involving access to Mastercard assets, information, and networks comes with an inherent risk to the organization and, therefore, it is expected that every person working for, or on behalf of, Mastercard is responsible for information security and must: • Abide by Mastercard’s security policies and practices; • Ensure the confidentiality and integrity of the information being accessed; • Report any suspected information security violation or breach, and • Complete all periodic mandatory security trainings in accordance with Mastercard’s guidelines. In line with Mastercard’s total compensation philosophy and assuming that the job will be performed in the US, the successful candidate will be offered a competitive base salary and may be eligible for an annual bonus or commissions depending on the role. The base salary offered may vary depending on multiple factors, including but not limited to location, job-related knowledge, skills, and experience. Mastercard benefits for full time (and certain part time) employees generally include: insurance (including medical, prescription drug, dental, vision, disability, life insurance); flexible spending account and health savings account; paid leaves (including 16 weeks of new parent leave and up to 20 days of bereavement leave); 80 hours of Paid Sick and Safe Time, 25 days of vacation time and 5 personal days, pro-rated based on date of hire; 10 annual paid U.S. observed holidays; 401k with a best-in-class company match; deferred compensation for eligible roles; fitness reimbursement or on-site fitness facilities; eligibility for tuition reimbursement; and many more. Mastercard benefits for interns generally include: 56 hours of Paid Sick and Safe Time; jury duty leave; and on-site fitness facilities in some locations. Pay Ranges O'Fallon, Missouri: $115,000 - $184,000 USD