Senior Backend Software Engineer - Customer Checkout Team

 

At Scalapay, we’re shaping a culture with high standards, independent and critical thought, innovation, ownership, and continuous learning. We operate in a fast-moving, tech-driven environment, and we’re looking for people who thrive in change, think boldly, and take initiative.

If you’re ready to put your potential to the test in a hiring process designed to spotlight exceptional talent, this is your chance to stand out and grow with one of Europe’s most ambitious fintech teams.

#MakeItHappen #PlayAsATeam #StayCurious #FocusOnCustomer.

The Mission

We're seeking a skilled Backend Developer to join our Experiences team at Scalapay. You'll be responsible for building and maintaining high-performance, scalable REST APIs that power our user experience. This role focuses on delivering exceptional user experiences through robust backend architecture and optimized API performance.

Key Responsibilities:

API Development & Performance

• Design, build, and maintain high-quality REST APIs using NestJS framework
• Optimize API performance through caching strategies, query optimization, and payload compression
• Implement rate limiting, pagination, and filtering for scalable data handling
• Ensure APIs meet performance benchmarks with sub-200ms response times

Security & Compliance

• Implement robust authentication and authorization systems (JWT, OAuth2, multi-factor authentication)
• Apply security best practices including input validation, SQL injection prevention, and XSS protection
• Ensure PCI DSS compliance for payment processing and sensitive data handling
• Implement API security measures including HTTPS/TLS, API key management, and request signing
• Design secure data encryption at rest and in transit

Backend Architecture

• Develop scalable, maintainable backend services using NestJS with TypeScript Design and implement microservices architecture patterns
• Apply dependency injection, modular architecture, and clean code principles
• Build event-driven systems and real-time features using WebSockets

Database & Cloud Infrastructure

• Work with MySQL databases, optimizing queries and implementing proper indexing
• Design efficient database schemas and manage migrations
• Deploy and manage applications on AWS infrastructure
• Implement containerization with Docker and CI/CD pipelines
• Monitor system performance and implement logging/tracing solutions

Required Qualifications:

Technical Skills

• 5+ years of backend development experience
• 3+ years hands-on experience with NestJS and TypeScript/JavaScript
• Strong proficiency in MySQL database design, optimization, and query performance
• Extensive experience with AWS services (EC2, RDS, Lambda, API Gateway, CloudWatch)
• Proven expertise in GraphQL API development (both code-first and schema-first approaches)
• Deep understanding of REST API design principles and best practices

Performance & Security Focus

• Demonstrated experience in API performance optimization and bottleneck identification
• Knowledge of caching strategies (Redis, Memcached, HTTP caching)
• Experience with database query optimization and indexing strategies
• Strong background in API security including authentication, authorization, and data protection

Development Practices

• Experience with Git version control and collaborative development workflows
• Knowledge of testing frameworks (Jest, unit testing, integration testing)
• Advanced understanding of security best practices (JWT, OAuth2, data encryption, secure coding)
• Experience with security testing and vulnerability assessments
• Experience with agile development methodologies

What We're Looking For:

• Performance-minded developer who naturally thinks about optimization and scalability
• Security-conscious professional who prioritizes secure coding practices and compliance
• Strong problem-solver who can identify and resolve API bottlenecks and security vulnerabilities