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Senior Software Engineer

Job in O'Fallon, St. Charles County, Missouri, 63366, USA
Listing for: MasterCard
Full Time position
Listed on 2026-06-06
Job specializations:
  • Software Development
    Senior Developer, Software Engineer
Job Description & How to Apply Below
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, 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 cloud‑native platforms.

* Evaluate technical trade‑offs and guide design decisions that ensure long-term system sustainability.

Software Development & Quality

* Independently design, build, test, deploy, and maintain high‑quality 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, root‑cause 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…
Position Requirements
10+ Years work experience
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