Senior Software Engineer

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
Who is Mastercard?
Mastercard is a global technology company in the payments industry. Our mission is to connect and power an inclusive, digital economy that benefits everyone, everywhere by making transactions safe, simple, smart, and accessible. Using secure data and networks, partnerships and passion, our innovations and solutions help individuals, financial institutions, governments, and businesses realize their greatest potential.
Our decency quotient, or DQ, drives our culture and everything we do inside and outside of our company. With connections across more than 210 countries and territories, we are building a sustainable world that unlocks priceless possibilities for all.
About the Role
As part of the Clearing Program within Core Payments, this role is responsible for designing, building, and operating solutions that support end-to-end clearing and settlement processing for credit and debit offline transactions. The Global Clearing Management System (GCMS) processes transaction data exchanged between acquirers and issuers, applies edits, assesses fees, and derives settlement values to ensure accurate financial reconciliation. The role plays a critical part in ensuring compliance with Mastercard processing standards, maintaining data integrity, and enabling reliable, high-volume transaction processing across global payment networks.
Role
As a Senior Software engineer, you will be responsible for development, deployment support, owning the delivery of user stories, mentoring junior team members, and performing code reviews. This is a vital role responsible for planning, developing, and coordinating all activities related to design, development, and implementation. We are seeking a highly motivated, detail-oriented, and proactive engineer who has the ability to operate under pressure in an independent, autonomous environment.
Responsibilities
Software Engineering & Development
- Design, build, test, deploy, and maintain software components, automation frameworks, and validation tools
- Apply strong knowledge of data structures, algorithms, and efficient coding practices in building scalable solutions
- Contribute to end-to-end software development lifecycle, including design, development, testing, deployment, and monitoring
Architecture & Design
- Participate in defining software architecture and design patterns to ensure scalability, reliability, and maintainability
- Ensure systems are designed for testability, observability, performance, and operational readiness
- Provide input into microservices and cloud migration strategies
Quality Engineering & Testing
- Develop and implement test automation frameworks and CI/CD integration pipelines (e.g., Jenkins, XLR)
- Design comprehensive test strategies and plans, including performance, reliability, and production simulation testing
- Ensure high code quality and coverage using tools such as Sonar or Clover
Security & Compliance
- Apply and promote secure coding practices, including code analysis, vulnerability detection, and mitigation strategies
- Integrate security testing into CI/CD pipelines
Code Quality & Reviews
- Conduct and lead code reviews, ensuring adherence to coding standards, security practices, and maintainability
- Act as a technical reviewer for system designs, test strategies, and implementation approaches
Operability & Performance
- Ensure systems are observable, monitorable, and resilient across environments
- Perform performance engineering, including load testing, tuning, and bottleneck analysis
- Troubleshoot complex production issues and ensure rapid resolution
Collaboration & Leadership
- Partner with developers, architects, and product teams to drive engineering best practices
- Mentor junior engineers and contribute to knowledge sharing across teams
- Evaluate and recommend tools, technologies, and frameworks for continuous improvement
All About You
Strong hands-on experience in software engineering, including development and quality engineering to design systems for reliability, performance, and scalability
Proven experience working with:
- JAVA JDK 11-17, Spring Boot, Spring Security, Maven, Hibernate / JPA, REST, and SQL Server or other object-oriented languages, front-end frameworks, and/or relational database technologies.
- Event Driven Framework, Full APIs and JSON/SOAP based API.
- SQL, Multi-threading, Message Queuing, & Distributed Systems.
- Nunit/Junit or other automated unit testing frameworks.
- Splunk alerting and monitoring solutions.
- Unit, functional, and integration testing
- Performance testing and engineering
Strong knowledge and understanding of:
- Cloud native developments, such as Pivotal Cloud Foundry (PCF), AWS, Etc.,
- Software design principles (OOP, modularity, design patterns)
- Software architecture concepts (microservices, distributed systems, scalability)
- Data structures and algorithms
- Experience with secure coding practices and application security principles (e.g., OWASP)
- Ability to contribute to system design and architecture decisions
Preferred Qualifications
- Domain knowledge in payments and transaction processing systems
- Bachelor's or master's degree in computer science or equivalent experience is preferred
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 [email protected] 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