Senior Backend Software Engineer - Consumer Banking

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 Scalapay is an AI-first international fintech. We're looking for a Backend Software Engineer with banking platform experience to join our Consumer Banking team. You'll design and deliver high-performance, secure and scalable APIs that power our customer experience. You'll work spec-first: you define what good looks like, and AI coding agents help you build it faster without lowering the bar on quality, security or compliance. Key Responsibilities: AI-First Engineering Write clear specifications and technical designs that AI coding agents (e.g. Claude Code) implement from, then direct, review and test their output; Take full ownership of AI-generated code, making sure it meets our standards for security, performance and PCI DSS compliance before it ships; Use AI across the whole development lifecycle: test generation, code review, documentation, debugging and incident analysis; Help shape the team's AI tooling, shared context, prompts and guardrails so that development becomes more automated over time. API Development & Integration Design, build and maintain high-quality REST APIs using NestJS and TypeScript; Meet performance targets of under 200ms response time through caching, query optimisation, payload compression, rate limiting, pagination and filtering; Integrate with external services and banking partners, keeping the platform resilient to third-party failures. Architecture Build scalable, maintainable microservices using dependency injection, modular design and clean code principles; Develop event-driven systems and real-time features. Security & Compliance Implement authentication and authorisation (JWT, OAuth2, MFA) and API security measures (TLS, API key management, request signing); Apply secure coding practices, including input validation and protection against SQL injection and XSS; Ensure PCI DSS compliance and encryption of sensitive data at rest and in transit. Data & Infrastructure Design efficient MySQL/PostgreSQL schemas, manage migrations and optimise queries and indexing; Deploy on AWS with Docker, EKS, and CI/CD pipelines, working with DevOps on infrastructure requirements; Monitor system performance through logging, tracing and alerting. Required Qualifications 5+ years of backend development experience, including banking platforms, system integrations and ledgers 3+ years with NestJS and TypeScript, or comparable frameworks and languages Proven AI spec-driven development: you've shipped production software by specifying, directing and validating the work of AI coding agents Strong MySQL and/or PostgreSQL skills: schema design, query optimisation and indexing Deep knowledge of REST API design, plus GraphQL experience (code-first and schema-first) Track record of finding and fixing API performance bottlenecks, including caching (Redis, Memcached, HTTP caching) Strong API security background: authentication, authorisation, encryption, security testing and vulnerability assessment Experience with AWS (EC2, RDS, Lambda, API Gateway, CloudWatch) or a comparable cloud platform Solid testing practice (Jest, unit and integration testing), Git workflows and agile delivery What We're Looking For Banking platform experience. You’ve built or worked on banking systems, including system integrations and ledgers. An AI-first builder. You can show us AI projects that demonstrate your spec-driven way of working, and you have good judgement about when to trust AI output and when to challenge it. An owner. You think about performance, scalability and security by default, not as an afterthought. A collaborator. You're comfortable with code reviews and enjoy sharing what you learn, including the AI workflows that work for you. A continuous learner. You keep up with backend, security and AI-assisted engineering practices. Why Join Scalapay Attractive packages based on skills and experience, the salary band we have for this position is of EUR 65'000 - 80'000 (Gross Annual Salary); An international fintech with an AI-first approach, raising the bar daily on how we build software and solve complex problems Work alongside industry tech leaders focused on exceptional user experiences Personalised support to grow your career and take ownership of the products you deliver Modern technology and the freedom to bring your own flair Recruitment Process: A quick chat with one of our Talent Acquisition team members The first interview with the Hiring Manager to dive deep into your experiences and better understand your motivation A case study to test your hard skills A final chat with Simone, our CEO Want to learn more? Don't hesitate to explore our Careers website , our LinkedIn and Glassdoor pages. Pro tip: send your CV in English 😉 Super Pro tip: we know that application processes can be scary and frustrating but… we look for talent, not people that tick all our boxes.