Design Online Shopping System like Amazon

Difficulty: Hard

Source: awesome-low-level-design

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Requirements

1. Browse products, add to cart, place orders
2. Multiple product categories with search
3. Manage profiles, view order history, track status
4. Inventory management
5. Multiple payment methods
6. Concurrent access
7. Scalable
8. User-friendly

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Class Diagram

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Classes, Interfaces and Enumerations

Class/Interface	Description
User	Id, name, email, password, orders list
Product	Id, name, description, price, quantity; update quantity, check availability
Order	Id, user, order items, total, status
OrderItem	Product, quantity
OrderStatus	Enum: pending, processing, shipped, delivered, cancelled
ShoppingCart	Add, remove, update items; map of product IDs to order items
Payment	Interface; CreditCardPayment implementation
OnlineShoppingService	Singleton; synchronized

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Design Patterns Used

Pattern	Application
Singleton	OnlineShoppingService provides centralized management of users, products, and orders with synchronized access

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Code Implementations

Language	Source Code
Java	View on GitHub
Python	View on GitHub
C++	View on GitHub
C#	View on GitHub
Go	View on GitHub