Senior Software Engineer - (C# or Java)

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 - (C# or Java) Mastercard Open Finance is transforming the account‑to‑account payments ecosystem. We deliver secure, scalable connectivity to over 3,000 financial institutions in 20 global markets, empowering users with control over their financial data and enabling trusted connections between financial institutions and third‑party providers. Our platform fuels innovation across payments while safeguarding security and privacy at scale. The Role We’re looking for a Senior Software Engineer to join our Connectivity division – the team that ensures our platform integrates flawlessly with thousands of bank and financial institution APIs. You’ll tackle reliability at scale, low latency, and regulatory complexity, working in a flat, collaborative team where engineers own features end‑to‑end. What You’ll Work On • Design, develop, and maintain APIs and integration modules connecting our platform to thousands of European banks and financial institutions. • Collaborate with engineers and product stakeholders to define requirements, set acceptance criteria, and deliver solutions. • Contribute to architecture by ensuring scalability, maintainability, and adherence to best practices. • Maintain quality through code reviews, testing, and continuous improvement initiatives. • Solve complex problems involving performance, distributed systems, and regulatory constraints. Our Stack • .NET 8 • Java • Cloud‑agnostic microservices architecture What We're Looking For • Strong experience building backend services in either .NET or Java, with a willingness to work across both where needed. • High proficiency in one language, plus some level of experience or ability to transition into the other with support. • Experience working in fast‑paced, product‑centric environments. • Solid understanding of API design, distributed systems, and cloud environments. • Experience in establishing bank connections through PSD2 interfaces. • Ability to write clean, maintainable, and testable code. • Collaborative mindset and eagerness to work closely with product and engineering peers. • Curiosity and drive to continuously improve systems, processes, and yourself. Why Join Us? • Impact at scale • Work on integrations that touch millions of users across Europe. • Small team, big responsibility • Lean environment where contributions matter daily. • Cutting‑edge fintech • Shape the future of open banking in one of Europe’s fastest‑moving ecosystems. • Join Mastercard Open Finance and help us elevate quality, drive innovation, and shape the future of open banking. 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. Everyone wants easier ways to pay; we invent them. Checkout lines are slow; we speed them along. Merchants want more sales; we give them data and insights. People need financial access; we connect them. Corporate purchasing is complicated; we make it simple. Commuters are busy; we speed ... (truncated, view full listing at source)