The Architecture Behind High-Performance E-Commerce

When an e-commerce platform handles millions of transactions daily, every architectural decision matters. Here is the stack and the thinking behind a recent platform I built that sustains sub-50ms API latency under peak load.

Event-Driven Core

The foundation is an event-driven architecture. Every action — add to cart, checkout, payment — produces an event. Downstream services consume these events asynchronously, enabling loose coupling and horizontal scaling.

Read/Write Separation (CQRS)

We separate read and write paths. Writes go to PostgreSQL with strict consistency. Reads are served from Redis-backed materialized views optimized for each query pattern. This eliminates expensive JOINs on the hot path.

Intelligent Caching Layers

Three caching layers work together:

1. CDN edge cache for static assets and product pages
2. Redis for session data, cart state, and inventory counts
3. In-memory LRU in the application layer for frequently accessed catalog data

Real-Time Inventory

Inventory accuracy is critical. We use PostgreSQL advisory locks for atomic stock reservation during checkout, with a background reconciliation process that corrects any drift every 60 seconds.

Search and Recommendations

Product search uses Elasticsearch with custom analyzers for Italian and English. Recommendations are generated by a collaborative filtering model retrained nightly, served via a FastAPI microservice with sub-10ms response times.

Observability

Every request is traced end-to-end with OpenTelemetry. Dashboards track p50/p95/p99 latency, error rates, and business metrics in real time. Alerts fire before users are impacted.