The Billing & Inventory Management System is a production-ready web application designed for grocery and retail stores to streamline daily operations.It enables store owners to generate customer bills, manage product inventory, track stock levels, and automatically create professional PDF invoices. The system includes a secure admin panel with session-based authentication, real-time billing calculations (subtotal, tax, discount, net payable), and full Pakistani Rupee (PKR) currency formatting.A complete REST API is implemented for inventory and billing operations, along with automated testing to ensure reliability. This project demonstrates strong skills in backend development, database modeling, authentication, API design, and deployment, and is suitable for small to medium-sized retail businesses.