Nexus Commerce

The Problem

A growing e-commerce brand had outgrown their monolithic Shopify-based stack. Flash sales were crashing the storefront, inventory sync was minutes behind, and adding new storefronts required duplicating the entire codebase.

The Solution

Nexus Commerce is a headless commerce backend built on a microservices architecture. A GraphQL API gateway (Apollo Federation) unifies 8 independent services — product catalog, inventory, pricing, orders, payments, users, shipping, and notifications — under a single coherent API.

Each service owns its own PostgreSQL database and communicates via async events over SQS. Redis handles session data, distributed locks during flash sales, and Lua-scripted inventory reservation to prevent overselling.

Infrastructure

All infrastructure is defined in Terraform and deployed to AWS. ECS Fargate services auto-scale independently based on custom CloudWatch metrics. A multi-region read replica setup keeps catalog queries fast globally.