Senior Software Engineer - Integrations & API Connectivity

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 - Integrations & API Connectivity
Overview
Mastercard is a global technology company powering an inclusive, digital economy, enabling secure and seamless transactions across 210+ countries.
This role sits within Mastercard's Open Finance Europe - Connectivity team, responsible for building and operating scalable API integrations with financial institutions across Europe.
As a Senior Software Engineer, you will be a key hands-on contributor responsible for designing, building, and operating secure, reliable backend services. You will work on complex engineering problems, contribute to system design decisions, and deliver high-quality solutions that operate at scale in production environments.
What You'll Do• Design, develop, test, and support scalable APIs and backend services• Contribute to system design decisions with a focus on scalability, resilience, and performance• Deliver high-quality, production-ready code across the full software development lifecycle• Troubleshoot and resolve production issues, ensuring system stability and reliability• Participate in code reviews and uphold engineering best practices and standards• Implement effective testing strategies (unit, integration, end-to-end)• Collaborate with cross-functional teams including Product, Architecture, Security, and SRE• Improve observability, automation, and operational efficiency across services
Technology Stack• Backend: C#, .NET, Web APIs• Cloud: Azure (App Services, KeyVault, Blob Storage), AWS (S3, Redis, Microservices)• Data: PostgreSQL, Flyway• Practices: CI/CD pipelines, observability, secure development• Plus: Java / Spring Boot, AI-assisted tools (e.g., GitHub Copilot)
What You Bring - Required• 3-5 years of professional software engineering experience• Strong hands-on experience building cloud-based, distributed backend systems• Solid expertise in API development, scalability, and production support• Ability to solve complex technical problems with a structured, pragmatic approach• Strong understanding of SDLC, testing practices, and secure coding principles• Proven ability to own and deliver components/services independently• Strong collaboration and communication skills
Preferred• Experience in payments, banking, or Open Banking (PSD2) environments• Experience working with microservices architectures• Familiarity with observability, monitoring, and incident response practices• Exposure to AI-assisted development tools (e.g., GitHub Copilot)
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.