Senior Full-Stack / Mobile Developer for Pickup Ordering MVP

Main Skills Required: React Native, Expo, TypeScript, Node.js, PostgreSQL, REST APIs, webhooks, Stripe or similar payment systems, inventory/reservation logic, merchant dashboard development, authentication/authorization, cloud deployment, logging, monitoring, and clean mobile UX implementation. Estimated Scope Of Work: Project size: Medium to large MVP. This is not a basic website. It is a transactional mobile and merchant platform. Estimated length: 3-6 months depending on availability, final scope, and POS integration complexity. Experience level: Senior/expert only. Job Description: I am looking for a senior full-stack/mobile developer to build the MVP for a pickup ordering platform for food and beverage merchants. The product is a native iOS and Android customer app with a web-based merchant platform. The MVP focuses on fast pickup ordering, clean menu browsing, checkout, POS sync, merchant stock control, and a shadow inventory ledger to help prevent overselling. The customer app must feel fast, smooth, simple, and intuitive. Customers should be able to browse stores, view menus, add items to cart, choose pickup preference, pay, and receive confirmation with minimal friction. The merchant platform must be lightweight and practical. Merchants should be able to manage stock, view reservations/orders, configure item availability, and work with POS-integrated menu/order flows where possible. This is not a generic food delivery clone. The product is focused on pickup, freshness, stock reservation, and low-friction merchant operations. The initial use case is food and beverage merchants such as bakeries, cafes, dessert stores, and similar businesses. Core MVP features include: - iOS and Android customer app - Store browsing and menu browsing - Item pages, modifiers, cart, checkout, and receipts - Payment capture, refunds, and failed-payment handling - Merchant web dashboard - Merchant stock management - Shadow inventory ledger: available, reserved, committed, cancelled, refunded - Next-day reservation flow for selected high-demand items - POS integration through third-party middleware where possible - Admin/support tools for orders, payments, stock, and merchant issues - Logging, monitoring, staging/production setup, and handover documentation Important requirements: - Use GitHub from day one under client ownership - Provide architecture documentation before full build - Use milestone-based delivery - Demonstrate real working flows, not only UI screens - Include tests and evidence for payments, stock, orders, webhooks, and failure cases - Build with security basics: authentication, authorisation, role separation, signed webhooks, secret management, HTTPS, and audit logs Application instructions: Please do not send a generic proposal. In your response, briefly explain: 1. How you would structure the backend for orders, payments, and inventory reservations. 2. How you would prevent overselling if POS inventory is not perfectly real-time. 3. Your preferred tech stack and why. 4. Your experience with payments, POS integrations, ordering platforms, marketplaces, or inventory systems. 5. Your hourly rate, weekly availability, and estimated timeline for a pilot-ready MVP.