Full Stack Software Engineer

This role is ideal for a Middle Full-Stack Engineer with 3+ years of experience and strong skills in JavaScript/TypeScript, React (or Next.js), and Node.js. It suits someone comfortable building scalable web applications, designing REST/GraphQL APIs, working with databases like PostgreSQL or MongoDB, and deploying cloud-based systems with Docker and CI/CD. You should enjoy solving complex fintech problems, collaborating across teams, and integrating AI/ML capabilities into modern financial automation products.

1. How would you design a scalable full-stack architecture for a financial automation platform processing millions of transactions?
   I would separate the system into modular services with clear API contracts, using Node.js services for core business logic and scalable databases like PostgreSQL for transactional integrity. Caching layers and asynchronous processing ensure performance and reliability at scale.

2. How do you structure a modern React/Next.js frontend for complex financial workflows?
   I organize the application into feature-based modules with reusable components and strong TypeScript typing. Clear separation between UI, state management, and API services improves maintainability and scalability.

3. How would you design and implement REST or GraphQL APIs for financial data processing?
   I define clear schemas and validation rules, ensure idempotent operations for financial actions, and implement robust error handling. Proper authentication and rate limiting are essential to maintain security and reliability.

4. How do you optimize performance in full-stack applications handling large volumes of financial data?
   I use efficient database indexing, caching with Redis, asynchronous background jobs, and optimized API queries. Monitoring metrics helps detect bottlenecks early and maintain high system performance.

5. What is your approach to integrating AI/ML models into a production web application?
   I isolate AI services behind APIs, manage asynchronous inference requests, and implement monitoring around model latency and accuracy. Clear fallback mechanisms ensure system stability when AI services fail.

6. How do you ensure reliability and observability in distributed systems?
   I implement structured logging, health checks, metrics, and tracing using monitoring tools. Observability allows teams to quickly identify and resolve production issues.

7. What best practices do you follow when working with databases like PostgreSQL or MongoDB?
   I design efficient schemas, optimize queries, and ensure transactional consistency where required. Regular performance analysis and indexing strategies maintain scalability.

8. How do you design secure systems for financial applications?
   I enforce strong authentication and authorization, validate all inputs, encrypt sensitive data, and follow industry security practices. Regular audits and monitoring help maintain compliance.

9. How do you manage containerized applications and CI/CD workflows?
   I use Docker to standardize environments and automate builds, tests, and deployments through CI/CD pipelines. This ensures consistent releases and faster iteration cycles.

10. How do you collaborate effectively in a fast-paced startup environment?
    I communicate proactively with cross-functional teams, prioritize impactful work, and iterate quickly based on feedback. Ownership and transparency help maintain momentum while ensuring product quality.

JustPaid is building the next generation of AI-powered financial automation tools, helping businesses streamline billing and payment workflows at scale. We’re hiring a Full Stack Software Engineer (Remote) to design and ship scalable applications using React, Next.js, Node.js, TypeScript, and modern cloud infrastructure on AWS. You’ll build APIs, integrate AI/ML capabilities, and architect systems that process millions of financial transactions while collaborating closely with product and AI teams. This role offers competitive salary plus equity and the opportunity to shape high-impact fintech products in a fast-growing startup environment.