Senior Java Software Engineer Jobs in St Louis, MO

Our Purpose

Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, we're helping build asustainableeconomy where everyone can prosper. We support a wide range of digital payments choices, making transactionssecure, 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 EngineerWho 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, networks, partnerships, and passion, our innovations help individuals, financial institutions, governments, and businesses realize their greatest potential.
Our Decency Quotient (DQ) drives our culture and everything we do. Operating in more than 210 countries and territories, we are building a sustainable world that unlocks priceless possibilities for all.
Overview
The ADUEX Engineering organization is central to Mastercard's growth strategy, delivering scalable, secure, and innovative solutions that empower small and medium businesses globally. As part of a lean, high impact engineering team, you will help build scalable cloud-native software solutions from the ground up, solving complex technical problems at scale.
This role is ideal for a Senior Software Engineer who thrives in complex environments, takes ownership of system design and quality, and consistently applies advanced engineering practices to ensure reliable, high performing, and secure systems.
About the Role
As a Senior Software Engineer, you will act as a technical owner and key contributor across the full software lifecycle, from architecture and design through production operations.
Software Design & Architecture
Design and evolve scalable, maintainable, and secure software solutions, translating business and technical requirements into well-structured system designs.
Contribute to and influence architecture decisions, defining patterns, standards, and best practices for APIs, event driven systems, microservices, and cloudnative platforms.
Evaluate technical tradeoffs and guide design decisions that ensure long-term system sustainability.
Software Development & Quality
Independently design, build, test, deploy, and maintain highquality software components and services.
Apply advanced data structures and algorithms to solve complex problems efficiently and optimize system behavior.
Lead and actively participate in code reviews, ensuring high standards for readability, maintainability, performance, and security.
Coach and mentor peers through technical feedback, pairing, and informal guidance.
Performance Engineering
Proactively analyze and optimize application and system performance, scalability, and reliability.
Design and execute performance, load, and stress testing strategies.
Identify bottlenecks and drive tuning efforts across application, data, and infrastructure layers.
Testing & Reliability
Define and maintain comprehensive unit, functional, and integration testing strategies.
Promote test automation and quality gates to ensure consistent and reliable delivery.
Ensure systems behave predictably under normal and peak workloads.
Operability & Production Ownership
Design systems with operational readiness in mind, including observability, logging, monitoring, alerting, and resilience.
Take ownership of production health within owned areas, participating in incident diagnosis, rootcause analysis, and preventive improvements.
Continuously improve reliability, maintainability, and supportability throughout the system lifecycle.
Security & Compliance
Apply secure coding practices throughout the SDLC, adhering to Mastercard security standards and industry frameworks (e.g., OWASP, CWE).
Ensure vulnerabilities are proactively identified and mitigated using automated tooling and secure design principles.
Collaboration & Leadership
Partner closely with Product, Architecture, Site Reliability, and Security teams to deliver aligned solutions.
Influence team and crossteam technical decisions through expertise and datadriven recommendations.
Contribute to engineering communities, guilds, and knowledgesharing initiatives across Mastercard.
All About You
Proficiency and hands-on experience building agentic frameworks in Python/TypeScript.
Strong experience and proficiency with modern web stacks, including Angular and React, along with JavaScript/TypeScript and Node.js / Java microservices.
Proven experience with backend development with JAVA required
Familiarity with Spring Boot frameworks preferred
Solid understanding of data structures, algorithms, and performance optimization techniques.
Handson experience building and operating cloudnative systems (AWS/Azure), including APIs, eventdriven services, and distributed data stores (SQL, keyvalue, or document databases).
Proven expertise in secure coding practices and use of static and dynamic security analysis tools (e.g., Sonar, Checkmarx).
Strong experience with Gitbased workflows, branching strategies, and leading effective peer code reviews.
Demonstrated ability to design, implement, and maintain unit, service, and integration tests.
Experience analyzing and troubleshooting issues across applications and systems, including production environments.
Deep understanding of modern SDLC methodologies (Scrum, Kanban, SAFe) and when to apply them.
Experience with CI/CD pipelines, automation, and containerized deployments.
Familiarity with observability tools and operational best practices for missioncritical systems.
Bachelor's degree in Computer Science, Engineering, Information Technology, or equivalent practical experience is preferred.
Pay Ranges
Arlington, Virginia: $132,000 - $212,000 USD
O'Fallon, Missouri: $115,000 - $184,000 USDMastercard 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.