E-Commerce Inventory System

Project overview

This project implements an inventory and product catalogue management system for an e-commerce application. The main goal was to model a realistic backend structure where products are not stored as flat records, but as part of a hierarchy covering brands, categories, products and technical details.

The application also includes authentication and authorization concerns that are common in commercial backend systems: login flow, JWT token validation, secured endpoints and role-based access for administrative and customer-facing operations.

Problem solved

Simple catalogue applications often become difficult to maintain when product data grows. Categories, brands, stock levels, cart quantities and order status need to stay consistent across multiple user actions. This project explores how to structure that logic using Spring Boot, relational modelling and transactional service boundaries.

The system was designed to separate catalogue browsing, inventory management and user-specific shopping cart behaviour, while keeping the data model explicit and easy to extend.

Key features

• Hierarchical product catalogue model: Brand → Category → Product → Details.
• Shopping cart logic with session persistence and quantity validation.
• JWT security flow: login, token issuing, filter validation and protected endpoint access.
• Many-to-many user-role relationship for role-based access control.
• REST API endpoints for catalogue browsing, cart operations and order management.
• Admin-side CRUD operations for product and inventory management.
• Low-stock threshold handling with inventory event logging.
• Order lifecycle tracking from cart to confirmed purchase.

Architecture and backend design

The backend follows a layered Spring Boot structure with controllers, services, repositories and JPA entities. Controllers expose HTTP endpoints, service classes contain business rules, and repository interfaces handle persistence through Spring Data JPA.

The product model is intentionally hierarchical. This makes it easier to support category pages, brand filtering, product detail views and future catalogue search. The security layer uses Spring Security with JWT-based authentication so that stateless API access can be supported without relying only on server-side sessions.

Authentication and authorization

The application demonstrates a JWT-based security flow using Spring Security. After login, the user receives a token that can be sent with protected API requests. A security filter validates the token and loads the user context before role-based access rules are applied.

This approach is useful for API-first applications where the backend may later serve a separate front-end, mobile application or external integration.

Technical challenges

• Designing product relationships without making the database model too rigid.
• Keeping inventory quantity validation consistent during cart and order operations.
• Separating admin functionality from customer-facing API behaviour.
• Applying JWT authentication without mixing security concerns into business services.
• Preparing the project for future improvements such as checkout, payments and advanced search.

Technology stack

The project was built with Java, Spring Boot, Spring Security, Spring Data JPA, JWT, MySQL and REST API principles. The focus was on backend architecture, data modelling, authentication and maintainable service-layer logic.

Project links

The source code is available on GitHub as part of my portfolio of Java backend and software engineering projects.