Mastercard

Principal Software Engineer

O'Fallon, Missouri Full time

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

Principal Software Engineer

Role Overview:
We are seeking a Principal Engineer who is a deeply hands-on full-stack engineer and architect. This role owns the architecture, design, and implementation of large-scale platforms while remaining actively involved in coding and day-to-day technical execution. The ideal candidate has a strong track record building distributed system, modernizing legacy platforms, and delivering GenAI-enabled capabilities in complex enterprise environments.

The Role:
• Design, build, and deliver secure, production-grade software using clean, testable, and maintainable code.
• Own end-to-end architecture across full-stack systems, including service boundaries, APIs, data models, resiliency, security, and runtime behavior.
• Design, implement, and operationalize GenAI-powered solutions, including LLM-based services, retrieval-augmented generation (RAG) pipelines, embeddings, vector stores, and agent workflows.
• Prototype, evaluate, and introduce new technologies to modernize existing platforms and enable new product capabilities.
• Define and drive technical roadmaps focused on scalability, reliability, performance, security, and cost optimization, including GenAI-specific latency and cost considerations.
• Contribute across the full software development lifecycle, including architecture, design, development, code reviews, testing, documentation, deployment, and production support.
• Own and operate production systems with deep insight into dependencies, failure modes, operational risks, and performance characteristics.
• Establish and enforce secure engineering and responsible AI practices, including privacy, compliance, governance, and risk controls.
• Mentor engineers and influence technical direction through architecture reviews, design discussions, and code reviews.
• Partner closely with product, data, security, and platform teams across a global organization to deliver cohesive end-to-end solutions.
• Act as a technology evangelist through internal technical forums, external speaking opportunities, and thought leadership.


All About You:
• Bachelor’s or Master’s degree in Computer Science or a related field, or equivalent practical experience.
• Expert-level foundation in algorithms, data structures, distributed systems, and core computer science principles.
• 13+ years of hands-on experience building large-scale systems using Java, the Spring Framework, REST-based services, and batch processing frameworks such as Spring Batch.
• Strong experience designing and integrating GenAI solutions, including LLM orchestration, prompt design, embeddings, vector databases, retrieval-augmented generation, and evaluation techniques.
• Experience building GenAI solutions using enterprise or cloud platforms such as Azure OpenAI or equivalent managed LLM platforms.
• 5+ years of data engineering experience, including advanced Oracle SQL and PL/SQL, data modeling, and performance tuning.
• Strong experience working in Agile environments using frameworks such as SAFe and Scrum, with hands-on use of TDD and BDD practices.
• Deep DevOps ownership, including CI/CD pipelines, observability, automation, and production support for distributed systems.
• Strong Linux or UNIX experience with confidence operating large-scale systems in production environments.
• Proven experience designing scalable, fault-tolerant, and highly resilient platforms.
• Experience modernizing monolithic systems using patterns such as strangulation and anti-corruption layers.
• Deep understanding of modern software design principles, including SOLID, DRY, single responsibility, and clean architecture.
• Excellent written and verbal communication skills, with the ability to explain complex technical concepts to a wide audience.
• Experience building cloud-native systems using platforms such as PCF, OpenShift, Azure, or similar environments is a plus.

#AI1

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: $170,000 - $281,000 USD

Atlanta, Georgia: $170,000 - $281,000 USD

New York City, New York: $204,000 - $337,000 USD

Purchase, New York: $196,000 - $323,000 USD

San Francisco, California: $204,000 - $337,000 USD