Senior Software Development Engineer

The Senior Software Development Engineer is a senior individual contributor responsible for designing, developing, and supporting highly scalable distributed systems. This role combines deep technical expertise with mentorship responsibilities and ownership of critical software components from design through production support.

What You Will Do *Design software solutions and contribute to software architecture decisions that support scalability, maintainability, and operational excellence. *Translate complex product requirements into technical designs and implementation plans. *Lead development of modular, extensible, high-performance applications. *Design and implement comprehensive unit, functional, and integration testing strategies. *Analyze, optimize, and improve application performance, scalability, and reliability. *Apply secure coding practices and promote application security best practices. *Lead and participate in code reviews, ensuring adherence to engineering standards. *Design systems with observability, operability, and supportability as core principles. *Research emerging frameworks and technologies and recommend adoption where appropriate. *Mentor junior developers and support onboarding activities. *Troubleshoot and resolve complex production issues using root cause analysis techniques. *Support engineering excellence through continuous improvement, refactoring, and adherence to SOLID principles., 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.

*Strong hands-on experience with Java, Spring Boot, Kafka, REST APIs, JPA, and distributed systems. *Strong understanding of software design and software architecture principles. *Experience building highly scalable and resilient systems. *Experience implementing automated testing strategies and quality engineering practices. *Strong knowledge of performance engineering and production optimization. *Strong understanding of secure software development principles. *Experience leading code reviews and mentoring engineers. *Strong troubleshooting and analytical problem-solving skills. *Experience with microservices, cloud-native applications, and CI/CD. *Experience building AI-assisted applications, autonomous agents, or agentic workflows. *Agile Scrum experience.

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

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.