Senior Backend / Full-Stack Lead – E-commerce Platform Architecture

We need a senior engineer/architect who can own the technical foundation, not simply implement tickets. We are building a mobile-first cross-border e-commerce platform that allows customers to shop U.S. retailers through our app, add products to a unified cart, pay through our platform, and have orders received and shipped internationally. Responsibilities: Architect the backend, APIs, database and core platform services. Build and oversee unified cart, checkout, payments, orders, users and shipping workflows. Design a scalable retailer configuration/integration architecture. Build secure APIs consumed by our React Native application. Design PostgreSQL data models and maintain data integrity. Handle authentication, security, caching, queues, monitoring and deployment. Establish engineering standards and review work from existing developers. Identify architecture problems and edge cases before they reach production. Stack: TypeScript, Node.js/NestJS, PostgreSQL, REST APIs, AWS/cloud infrastructure. Who we're looking for: A genuine senior engineer who has architected and shipped production e-commerce, marketplace, fintech, logistics or similarly complex platforms. You must be comfortable making architecture decisions and taking technical ownership. Please do not apply if your experience is primarily basic CRUD applications.