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
Senior Software Engineer, Blockchain Team
Location: Lisbon, Portugal
Experience: 5+ years
Employment Type: Full-time
Overview
We are seeking a highly skilled Senior Software Engineer to join our Blockchain Team in Lisbon. In this role, you will design, develop, and maintain secure, scalable, and high-performance distributed systems that support blockchain-based products and services. You will collaborate with cross-functional teams to deliver innovative solutions while driving engineering excellence and mentoring other developers.
Key Responsibilities
• Design, develop, and maintain blockchain platforms and distributed applications.
• Build secure and scalable backend services using modern software engineering practices.
• Develop integrations with blockchain networks, digital asset platforms, and cryptographic services.
• Create and maintain APIs, microservices, and cloud-native applications.
• Participate in architecture discussions and influence technical direction.
• Ensure high availability, performance, security, and reliability of production systems.
• Experience with cryptographic protocols, key management, and secure data handling practices.
• Conduct code reviews and mentor junior and mid-level engineers.
• Collaborate with Product Managers, Architects, Security Engineers, and Operations teams.
• Drive automation, testing, CI/CD, and operational excellence initiatives.
• Troubleshoot complex technical issues across distributed environments.
Required Qualifications
• Bachelor's or Master's degree in Computer Science, Software Engineering, or a related field.
• 5+ years of professional software engineering experience.
• Strong proficiency in Java and Spring.
• Experience developing full-stack applications, including scalable backend services and modern, responsive frontend solutions.
• Strong hands-on experience with frontend framework Angular.
• Experience building responsive, accessible, and user-friendly web applications.
• Strong understanding of REST APIs, GraphQL, and frontend-backend integration patterns.
• Experience building scalable microservices and distributed systems.
• Strong understanding of cloud platforms such as AWS or Azure.
• Solid knowledge of software design patterns, system architecture, and performance optimization.
• Experience with CI/CD pipelines, containerization, Docker, and Kubernetes.
• Familiarity with modern testing frameworks for both frontend and backend development.
• Excellent problem-solving, communication, and collaboration skills.
• Ability to lead technical initiatives, mentor engineers, and drive best practices across the software development lifecycle.
Preferred Qualifications
• Experience with blockchain technologies such as Ethereum, Hyperledger, Bitcoin, Polygon, Solana, or similar platforms.
• Understanding of cryptography, PKI, digital signatures, encryption, and secure key management.
• Experience developing user interfaces for blockchain or digital asset platforms.
• Knowledge of Web3 technologies, wallet integrations, and smart contract interactions.
• Experience with event-driven architectures, messaging systems, and real-time applications.
• Experience designing and implementing secure authentication and authorization solutions (OAuth2, OIDC, MFA).
• Previous experience leading technical projects and mentoring engineers.
What Success Looks Like
• Delivering reliable and secure blockchain solutions to production.
• Improving…