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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Software Engineer II - **Company:** Mastercard - **Location:** O'Fallon, MO, United States - **Salary:** $92,000.0 - $147,000.0 - **Contract:** Permanent contract - **Skills:** Clean Code Principles, Application Programming Interfaces (APIs), Agile Methodology, Software Applications, Application Performance Management, Software Quality, Code Review, Cyber Security, Continuous Integration, Data Structures, Software Debugging, Software Design Patterns, HP Systems Insight Manager, Performance Tuning, Scrum Methodology, Software Architecture, Secure Coding, Software Engineering, Software Systems, Software Troubleshooting, Integration Tests, Solid Principles, Code Restructuring, Software Version Control - **Published:** September 28, 2026 - **Apply:** https://mastercard.wd1.myworkdayjobs.com/CorporateCareers/job/OFallon-Missouri/Software-Engineer-II_R-290657 ## About the Role *Experience developing, testing, deploying, and supporting software applications in an enterprise environment. *Ability to translate business requirements into secure, scalable, and maintainable software solutions. *Understanding of software design principles, software architecture concepts, and common design patterns. *Experience applying appropriate data structures and programming techniques to solve technical problems effectively. *Experience with unit, functional, and integration testing practices and tools. *Knowledge of secure coding standards and secure software development practices. *Experience participating in code reviews and following software quality best practices. *Strong troubleshooting, debugging, and problem-solving skills. *Understanding of performance optimization, scalability, reliability, and application monitoring concepts. *Familiarity with operational support, observability, maintainability, and production readiness practices. *Experience with source control, CI/CD pipelines, automation, and modern software delivery methodologies. *Familiarity with Agile development practices, including Scrum, Kanban, or similar frameworks. *Strong collaboration and communication skills with both technical and non-technical stakeholders. *Demonstrated ability to learn and adapt to new technologies, tools, and architecture patterns. ## Description Mastercard's Core Payments organization is seeking a Software Engineer II to contribute to the design, development, testing, deployment, and support of secure, scalable, and reliable software solutions that power critical payment capabilities across Network Solutions. This role is responsible for delivering high-quality software at the application and component level, collaborating with Product and engineering partners to translate business requirements into technical solutions, and supporting the full software development lifecycle. The ideal candidate combines strong software engineering fundamentals, problem-solving skills, and a commitment to engineering excellence through quality, security, performance, and operational best practices. Responsibilities *Design, develop, test, deploy, and support software applications and services throughout the software development lifecycle. *Translate business and technical requirements into scalable, maintainable, and secure software solutions. *Contribute to software design and architecture discussions, applying appropriate design patterns, application patterns, and engineering standards. *Write secure, high-quality code while adhering to established coding standards, secure development practices, and team processes. *Participate in code reviews to improve code quality, maintainability, security, and overall engineering excellence. *Develop and maintain unit, functional, and integration tests to ensure quality, reliability, and functional coverage. *Troubleshoot, debug, and refactor existing applications to resolve issues and improve system stability. *Analyze and optimize application performance, scalability, and reliability through monitoring, testing, and continuous improvement efforts. *Apply effective data structures and software engineering principles to build efficient and maintainable solutions. *Build software with operational readiness in mind, including observability, maintainability, production support, and reliability. *Participate in Agile planning, requirements elaboration, estimation, prioritization, and delivery activities with Product and Business stakeholders. *Utilize CI/CD pipelines, automation, source control, and modern software delivery practices to improve engineering efficiency and consistency. *Collaborate with peers to evaluate solutions, solve technical challenges, share knowledge, and support Engineering Guild initiatives. *Create and maintain technical documentation for software components, APIs, services, and delivered solutions. *Continuously learn and adopt new technologies, tools, and development approaches that support business and engineering objectives., 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. ## Related Videos - [Security Pitfalls for Software Engineers](https://www.wearedevelopers.com/videos/726-security-pitfalls-for-software-engineers) - [Are Code Reviews Worth It? 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