High-Performance eCommerce Platform
Scalable storefront and checkout built to survive peak sale-day traffic
Ongoing platform, in production since 2022
- Peak concurrent sessions
- 10k+
- Page load (p75)
- <1.2s
- Uptime on sale days
- 100%
Overview
A production eCommerce platform where the previous storefront degraded under promotional traffic spikes, and slow page loads were bleeding checkout conversion. Rebuilt the rendering and data layer so performance held under load instead of failing at the exact moment revenue was highest.
The Problem
Flash sales and promotions drove traffic spikes the existing architecture couldn't absorb — product pages slowed under load and checkout abandonment climbed exactly when conversion mattered most.
Architecture
Next.js storefront with ISR and edge caching for product/category pages; a NestJS commerce API backed by PostgreSQL with read replicas for catalog queries; Redis-backed cart and session state so checkout survives origin latency; CDN-fronted media to keep image-heavy pages fast on mobile.
Challenges and solutions
Challenges
- Sustaining sub-second page loads during promotional traffic spikes 10x above baseline
- Keeping cart state consistent across devices and tabs without double-charging or losing items
- Isolating read-heavy catalog traffic from write-heavy checkout traffic on the same database
Solutions
- Moved product and category pages to ISR + edge caching so traffic spikes hit the CDN, not the origin
- Added PostgreSQL read replicas dedicated to catalog/search queries, keeping the primary free for order writes
- Rebuilt cart state as a Redis-backed, optimistic-UI model reconciled server-side on checkout
Performance Improvements
- Cut median product-page load time from multi-second to sub-1.2s under peak load
- Eliminated sale-day downtime by decoupling catalog reads from order-write capacity
- Reduced checkout abandonment tied directly to page load latency
Business Impact
The platform now sustains peak sale-day traffic without degrading, converting a larger share of that traffic into completed orders instead of losing it to slow pages and cart errors.
Lessons Learned
Performance work pays for itself at the top of the funnel — checkout conversion is downstream of page load time, not a separate problem from it.
Stack
- Next.js
- NestJS
- PostgreSQL
- Redis
- AWS
- DigitalOcean