Software Development Engineer in Test; SDET II

Position: Software Development Engineer in Test (SDET) II
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

Software Development Engineer in Test (SDET) II

Overview:

Mastercard's Global Credit Card Authorization team is seeking a Software Development Engineer in Test (SDET) II to help ensure the quality, resilience, and performance of one of the most critical transaction processing platforms in the world. This platform facilitates billions of transactions annually between issuers, acquirers, and service providers across the globe.

In this role, you will apply your software development expertise to design and execute robust testing strategies for complex, high‑throughput systems. You will play a key role in raising engineering standards, strengthening production readiness, and embedding quality throughout the development lifecycle.

This is a hybrid role based in O'Fallon, MO, with an expectation of three days per week onsite.

Role:

* Develop comprehensive test plans based on high‑level design and technical documentation.

* Design, implement, and execute functional, integration, and User Acceptance Testing (UAT) test cases.

* Validate system behavior by analyzing application traces, logs, and metrics to ensure complete test coverage.

* Perform root cause analysis to identify, document, and track software defects.

* Partner with developers and engineers to remove testing blockers and ensure timely completion of test cycles.

* Ensure production readiness by proactively identifying and resolving defects prior to release deployments.

* Contribute to continuous improvement of test processes, tools, and quality practices.

* Actively participate in agile ceremonies, including story refinement and sprint planning.

* Collaborate effectively with cross‑functional teams in a fast‑paced, distributed environment.

All

About You:

* Experience as a Software Development Engineer in Test (SDET), Quality Assurance or Quality Engineer with previous experience developing and executing functional, integration, and UAT test strategies for complex systems.

* Ability to create detailed test plans from high‑level designs and requirements.

* Strong understanding of software quality practices, defect management, and test coverage methodologies.

* Hands‑on experience working in Linux environments.

* Experience with scripting languages, preferably shell scripting.

* Proficiency in C/C++ or Java for test development and system validation.

* Experience working in a team environment using source control tools, preferably Git.

* Strong analytical, critical‑thinking, and attention‑to‑detail skills.

* Excellent verbal and written communication skills, with the ability to articulate complex ideas clearly and concisely to both technical and non-technical stakeholders.

* Bachelor degree in Computer Science, Software Engineering, Information Technology, Mathematics, or a related field. Equivalent practical experience may also be considered.

This role is not eligible for Mastercard's work authorization sponsorship. As such, candidates must be eligible to work in the United States, now as well as in the future, without employer sponsorship.

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 and identify the type of accommodation or assistance you are requesting.

Do not include any medical or health information in this email. The Reasonable…