Software Development Engineer in Test (SDET) II

About the role

Mastercard’s Global Credit Card Authorization team is looking for a Software Development Engineer in Test (SDET) II to ensure the quality, resilience and performance of its high‑throughput transaction processing platform. Based in O’Fallon, MO, the role blends software development with testing expertise to embed quality throughout the product lifecycle.

Key responsibilities

• Develop comprehensive test plans from high‑level designs and technical documentation.
• Design, implement and execute functional, integration and User Acceptance Testing (UAT) test cases.
• Analyze application traces, logs and metrics to validate system behavior and achieve full test coverage.
• Perform root‑cause analysis, document defects and track their resolution.
• Collaborate with developers to remove testing blockers and ensure timely test cycle completion.
• Proactively identify and resolve defects to guarantee production readiness before releases.
• Contribute to continuous improvement of test processes, tools and quality practices.
• Participate in agile ceremonies such as story refinement and sprint planning.

Required profile

• Proven experience as an SDET, QA Engineer or Quality Engineer developing functional, integration and UAT 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 and with shell scripting.
• Proficiency in C/C++ or Java for test development and system validation.
• Experience using source‑control tools, preferably Git, in a collaborative team setting.

Required skills

• Linux
• Shell scripting
• C/C++
• Java
• Git