Full-Stack App Developer Needed to Build Mobile/Web App for Existing Hardware Business

We operate an established hardware business (ferretería) with an active website, and we are looking for an experienced developer (or team) to build a dedicated custom application (mobile/web) connected to our existing web platform and business logic. The application will streamline our B2B and B2C sales operations—handling heavy hardware logistics, custom sales quotes (proformas), fleet weight limits, distance-based shipping rates, and a custom customer loyalty rewards program. Below are the detailed scope of work and features required for the app: 1. Product Catalog Sync & Weight-Based Capacity Management Catalog Synchronization: Sync and load our existing product catalog into the app, complete with categories, stock, and item details. Product Weight & Dimensions: Every item must record weight and physical dimensions to calculate accurate freight capacity. Fleet Management Module: Backend management for our delivery fleet (listing vehicles by weight capacity, volume limits, and dimensions). 2. Distance-Based Freight & Smart Delivery Scheduling Distance-Based Logistics (Per Kilometer): Automatic calculation of freight costs based on delivery distance (kilometers). Freight totals require manual admin/sales review and approval before finalizing. Smart Delivery Slots: Customers can select their preferred delivery date and time window. The app must cross-reference available fleet capacity and current daily workload to prevent scheduling conflicts or overloading. 3. Proforma Invoicing & Sales Approval Workflow Proforma Creation: Customers can build and request a official proforma invoice directly inside the app. Sales Approval Gate: Proformas cannot be paid immediately. A designated salesperson must review and approve the request. Upon review/approval, the customer receives a notification to complete the payment. 4. Secure Payments & User Access Roles PayPal Integration: Integrated checkout using PayPal once a proforma is reviewed and approved by sales staff. Role-Based Access Control (RBAC): Multi-tier user logins and permissions for Customers, Sales Representatives, Dispatchers, and Administrators. 5. Customer Profiles & 6th-Purchase Loyalty Rewards Account Identification: Individual customers register via email, while corporate/business accounts register using their company name and RTN (Tax ID). Purchase Accumulation & Digital Stamp Card: The system automatically tracks completed orders per account. Upon completing their 6th qualifying purchase, the system automatically unlocks a complimentary promotional gift or special reward. Key Requirements & Preferred Skills: Proven experience building commercial e-commerce/retail apps connected to existing web infrastructures or ERP systems. Strong background in payment gateway integration (PayPal) and workflow automation (proforma approvals, capacity-based routing). Experience with inventory/logistics management software (weight and dimension calculations). High code quality, clear architecture, responsive UI/UX, and regular communication updates. If you have built similar applications for hardware distributors, retail stores, or logistics-heavy platforms, please submit examples of past projects alongside your proposal.