Senior Backend Developer

About the role

We are seeking an experienced Senior Backend Developer to join a fast‑moving fintech team in Portugal. You will help build and evolve secure, high‑performance backend services that power digital‑asset and blockchain platforms used by a global user base.

Key responsibilities

• Design, develop, and maintain backend services and APIs that support scalable financial and blockchain platforms.
• Collaborate with developers, product managers, designers, and stakeholders to translate requirements into efficient architectures.
• Improve and optimise existing Node.js services for scalability, performance and reliability.
• Create new microservices and integrate them across distributed systems using RPC and other communication methods.
• Write and optimise complex queries for operational, compliance and financial reporting in MySQL and MongoDB.
• Ensure backend systems follow strong security standards and best practices.
• Contribute to high‑availability architectures and real‑time service responsiveness as the platform scales globally.
• Participate in troubleshooting, debugging and continuous improvement initiatives.

Required profile

• Minimum 5 years of professional experience with JavaScript and Node.js in backend development.
• Strong understanding of microservices architecture and distributed systems.
• Proven experience building complex, high‑scale platforms.
• Hands‑on experience with relational (MySQL) and NoSQL (MongoDB) databases.
• Good knowledge of backend security principles and secure API design.
• Ability to quickly learn and adapt to new technologies.
• Familiarity with high‑availability, real‑time services and blockchain concepts.

Required skills

• JavaScript
• Node.js
• Microservices
• RPC communication
• MySQL
• MongoDB
• Relational databases
• NoSQL databases
• Backend security
• Secure API design
• High‑availability systems
• Real‑time services
• Blockchain fundamentals