Principal 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
Principal Software Engineer
About 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. With connections across more than 210 countries and territories, we are building a sustainable world that unlocks priceless possibilities for all.
Role Overview
As a Principal Engineer within the Decision Stream program, you will combine enterprise-scale technical leadership with hands-on engineering for the next-generation Decision Management Platform. This is not a strategy-only role. You will actively design, code, prototype, and validate core platform capabilities, using modern AI-assisted development tools as part of day-to-day software engineering to move faster, improve quality, and help teams adopt better ways of building.
Key areas of focus include leveraging disruptive technologies in real-time AI inferencing and decisioning to improve product effectiveness, increase business delivery, strengthen technical resilience, and lower cost of ownership. You will work closely with technology executives, senior leaders, and engineers to shape the overall AI & DPE technology strategy.
Key Responsibilities
Platform & Product Development
Build software, tooling, and platform capabilities.
Design and implement large scale distributed systems.
Develop reusable services, patterns, and integrations.
Contribute to new product and prototype development from concept through validation.
Evaluation & Technical Judgment
Evaluate systems, frameworks, and tools across quality, cost, latency, scalability, reliability, and maintainability.
Apply sound engineering judgment to trade-offs in distributed systems design and architecture.
Developer Experience & Enablement
Apply AI tools as part of daily engineering practice to real product and platform problems.
Teach and model the adoption of AI-assisted development, modern languages, and current engineering practices.
Improve developer experience through automation, AI-assisted workflows, and platform thinking.
Advocate learnings, prototypes, and best practices across the organization.
Customer Experience & Platform Strategy
Own and improve end-to-end customer experience across a portfolio of services and applications.
Simplify and optimize architecture strategies to balance cost, performance, and business value.
Apply judgment and experience to make trade-offs between competing priorities and technical constraints.
Thought Leadership & Influence
Lead architectural design for complex, enterprise-wide initiatives spanning multiple services and programs.
Drive organization-wide initiatives to advance software engineering craftsmanship and best pratices.
Represent the organization through public speaking, technical blogs, and white papers on emerging technologies.
Participate in Principle-level architecture reviews and resolve enterprise-wide technical and regulatory challenges.
Talent & Culture
Mentor engineers at all levels, fostering technical growth and leadership.
Conduct technical interviews to raise the performance bar and attract top talent.
Provide unbiased, accomplishment-based recommendations for promotions.
Champion AI-assisted engineering as a default working practice and align it with organizational values.
What We're Looking For
You are an awesome engineer and leader who is passionate about joining a like-minded team at Mastercard AI & Decision Product Enablement. You thrive on solving complex engineering challenges at scale and have experience building high-speed streaming platforms or distributed systems at hyperscaler-level performance.
AI-native engineer - uses AI-assisted development as default
Innovation leader - builds systems at massive scale and availability
Streaming-first mindset - experience with low-latency pipelines
Proven outcomes - delivers impactful, production-ready systems
Engineering culture champion - drives best practices and transparency
Collaborative - works across engineering and data science teams
Technical Domains
Candidates are not expected to be expert in all areas but should demonstrate hands-on depth and expertise in one or more of the following:
Decisioning Data & Feature Platforms
Data architectures for decisioning: lakehouses, delta lakes, distributed logs, and product-aligned data models.
Feature catalogs and engineering platforms for reusable, governed features that can be defined, discovered, validated, and served across batch and real-time decisioning.
Decisioning data models covering events, derived features, reference data, labels, outcomes, and policy data consumed by rules, models, and agentic workflows.
Data contracts, lineage, freshness, and quality controls that keep decisioning data trustworthy, explainable, and production ready.
High-Throughput, Low-Latency & Real-Time Systems
Event streaming and high-throughput data pipelines.
Low-latency data technologies -distributed caches, in-memory data grids.
Real-time transaction processing and sub-second decisioning.
AI & ML Systems
ML lifecycle engineering: model training, deployment, refresh, and low-latency inference.
Agentic AI patterns, LLM integration, and prompt engineering applied to platform and product problems.
Model observability, drift detection, and feedback loops that keep AI systems reliable in production.
Decisioning Tooling & UX
Authoring, testing, and deployment of business rules engine rules and similar decisioning logic.
Tooling that helps authors validate rules, models, and policies pre-deployment.
Operator experience for authors, analysts, and SREs: lifecycle, approvals, observability, and explainability of live decisions.
Rules engine design and modernization.
Cloud Infrastructure, Platform Engineering & DevOps
AWS infrastructure engineering and cloud-native platform patterns.
DevOps and platform engineering -automation, CI/CD, observability, GitOps.
Requirements
Extensive experience in software engineering and technical leadership
Proven delivery of large-scale distributed systems
Expertise in cloud, AI/data platforms, and modern engineering practices
Strong communication and mentorship skills
Bachelor's degree (or equivalent); advanced degree preferred
Telecommuting and/or working from home may be permissible pursuant to company policies.
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: $170,000 - $281,000 USD