Senior Software Engineer

MastercardO'fallon, MO
$115,000 - $184,000Onsite

About The Position

The CORE Payments Optimization team is seeking a Senior Software Engineer to build and enhance critical payment processing services that support issuer account management, transaction controls, and card lifecycle management across Mastercard's global network. This role is ideal for an experienced software engineer who enjoys solving complex distributed systems challenges, designing scalable event-driven solutions, and working with high-volume payment processing applications. The successful candidate will contribute across the full software development lifecycle, from architecture and design through implementation, testing, deployment, optimization, and operational support. The position requires strong expertise in Java-based application development, Spring Boot, Kafka, PostgreSQL, and modern software engineering practices, along with the ability to influence technical direction and mentor other engineers.

Requirements

  • Strong experience developing enterprise applications using Java and Spring Boot.
  • Experience building event-driven architectures utilizing Kafka or similar messaging technologies.
  • Strong understanding of software development principles, object-oriented programming, and distributed systems.
  • Experience designing and developing REST APIs and microservices architectures.
  • Hands-on experience with PostgreSQL or other relational database platforms.
  • Experience implementing automated testing strategies including unit, functional, and integration testing.
  • Strong troubleshooting and root cause analysis capabilities within complex production environments.
  • Experience conducting code reviews and promoting engineering best practices.
  • Knowledge of secure coding principles and application security standards.
  • Experience optimizing application performance, scalability, and reliability.
  • Strong understanding of software design patterns, data structures, and algorithms.
  • Excellent communication, collaboration, and problem-solving skills.

Nice To Haves

  • Experience with Spring Batch processing frameworks.
  • Experience supporting mission-critical transaction processing systems.
  • Familiarity with cloud platforms and containerized deployments.
  • Experience with CI/CD pipelines and DevOps engineering practices.
  • Knowledge of observability tooling, application monitoring, and operational excellence practices.
  • Experience within financial services, payments, or highly regulated environments.

Responsibilities

  • Design, develop, test, deploy, and support scalable software solutions that power Mastercard's payment processing ecosystem.
  • Build and maintain event-driven applications utilizing Kafka and distributed messaging patterns to process high-volume transaction workloads.
  • Develop microservices and backend services using Java, Spring Boot, and Spring Batch frameworks.
  • Design database solutions utilizing PostgreSQL and optimize data access patterns for performance, reliability, and scalability.
  • Contribute to software architecture decisions and help modernize existing applications through scalable, maintainable engineering practices.
  • Analyze business and technical requirements and translate them into robust software designs that balance functionality, performance, security, and operational excellence.
  • Create and maintain comprehensive unit, functional, and integration tests to ensure software quality and reliability.
  • Conduct code reviews and provide constructive feedback to improve software quality, maintainability, and adherence to engineering standards.
  • Troubleshoot and resolve complex application, system, and production issues across distributed platforms.
  • Apply secure coding practices and proactively address security vulnerabilities throughout the software development lifecycle.
  • Collaborate with Product, Architecture, Platform Engineering, Operations, and partner teams to deliver enterprise-scale solutions.
  • Design systems with observability in mind by implementing logging, monitoring, metrics, and alerting capabilities that improve operational readiness.
  • Optimize applications and services to meet performance, scalability, availability, and reliability objectives.
  • Support production readiness activities, incident management, root cause analysis, and continuous improvement initiatives.
  • Mentor and coach engineers through technical leadership, knowledge sharing, and engineering best practices.
  • Continuously evaluate emerging technologies and engineering approaches that improve development productivity and platform capabilities.

Benefits

  • 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
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