Zapper is a dual-module grocery delivery application built with React Native for the mobile client and Node.js for the backend, with PostgreSQL for data management and Docker for deployment. The system supports separate User and Rider workflows, allowing customers to browse products, manage carts, select delivery locations, place orders, and monitor order progress, while nearby riders receive and fulfill assigned deliveries. The app integrates Google Maps for address selection and live rider tracking, Firebase Authentication for secure sign-in, and KYC verification to support trusted user and rider onboarding. It also includes order timeline management, wallet and transaction handling, and end-to-end delivery flow for a reliable grocery ordering experience.