Senior Backend Developer

About the role

We are seeking a Senior Backend Developer to join a fast‑growing fintech team in Belgium. You will help design, build, and maintain high‑performance backend services that power digital asset and blockchain platforms used by a global user base.

Key responsibilities

• Design, develop and maintain scalable backend services and APIs for financial and blockchain applications.
• Collaborate with product managers, designers and other engineers to translate business needs into robust architecture.
• Improve existing Node.js services for better performance, reliability and security.
• Create new microservices and integrate them across distributed systems using RPC and other communication patterns.
• Write and optimise complex queries for operational, compliance and financial reporting.
• Ensure backend systems follow strict security standards and best practices.
• Contribute to high‑availability and real‑time service design as the platform scales globally.
• Participate in debugging, troubleshooting 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 track record delivering 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 new technologies and adapt to evolving technical environments.

Required skills

• JavaScript
• Node.js
• MySQL
• MongoDB
• RPC
• Microservices
• Distributed systems
• Backend security
• High‑availability architectures
• Real‑time services
• Blockchain concepts