ShopSphere Microservices E-Commerce
Production-ready Java e-commerce backend with Spring Boot microservices, API Gateway, Eureka/Config, JWT, Kafka workflows, Redis carts, and PostgreSQL.
Overview
ShopSphere is a production-ready Java e-commerce backend built as a Spring Boot microservices system. It gives any frontend a single API Gateway entry point while separate services handle auth, catalog, cart, orders, inventory, payments, notifications, discovery, and centralized configuration.
The Problem
A lot of e-commerce demos combine everything into one backend or skip the distributed-system parts entirely. I wanted to build the backend architecture a real store could grow into: independently owned services, secure client access, fast cart operations, reliable async order workflows, and clear API contracts.
What I Built
- 1A Java 21 / Spring Boot 3.3.5 multi-module Maven backend with service-registry, config-service, api-gateway, user, product, cart, order, inventory, payment, notification, and common event modules.
- 2A Spring Cloud Gateway front door on port 8080 so every client uses one REST + JSON API surface instead of calling services directly.
- 3JWT authentication for registration and login, with protected routes enforced at the gateway and user-service layers.
- 4Service discovery with Eureka and centralized Spring Cloud Config so service URLs and configuration are not hardcoded across the system.
- 5Redis-backed cart storage for low-latency cart operations separate from durable order and catalog data.
- 6PostgreSQL persistence with schema ownership per service, keeping service data boundaries explicit while using one local database instance.
- 7Kafka event flows for order-created, payment, inventory, low-stock, and notification workflows, with shared event contracts in a common library.
- 8Dockerfiles for each service plus Docker Compose infrastructure for PostgreSQL, Redis, Kafka, and Zookeeper.
- 9Swagger/OpenAPI documentation on each service for frontend integration, Postman workflows, and future SDK generation.
Key Technical Decisions
Gateway-first API design
All frontend traffic goes through Spring Cloud Gateway, giving clients one base URL while the backend keeps services independently deployable and discoverable through Eureka.
Event-driven order workflow
Orders publish domain events into Kafka so inventory deductions, payment simulation, low-stock handling, and notifications can run asynchronously without tightly coupling services.
Service-owned data boundaries
Each service owns its persistence model and schema. Product catalog, orders, inventory, payments, users, and notifications remain isolated enough to evolve or scale independently.
Outcome
A complete backend platform for an e-commerce product: authenticated users, searchable catalog, Redis cart, order lifecycle, inventory tracking, payment simulation, notifications, service discovery, config, OpenAPI docs, and containerized infrastructure.
What I Learned
The biggest design challenge was coordinating service boundaries without turning every request into a chain of blocking calls. Kafka helped decouple the order flow, while the gateway and shared event library kept frontend integration and inter-service contracts understandable.