""Key Brains challenged our assumptions at every turn and designed something far better than our original spec." — James Whitfield, CTO"
The Challenge
StyleHub had grown from a single-brand retailer to an 80-vendor marketplace on infrastructure that was never designed for it. Black Friday exposed every design flaw simultaneously: the database deadlocked, the cache layer fell over, and checkout processing queued for up to 47 minutes.
Our Approach
We used a strangler-fig migration — running old and new systems in parallel to preserve business continuity throughout the 8-month rebuild.
- Seven microservices on Amazon EKS, each independently deployable
- Elasticsearch with 12 fashion-specific analysers for product search
- Real-time inventory sync via webhooks and Redis Pub/Sub — updates in under 2 seconds
- Stripe Connect for automated multi-currency vendor payouts
Results
The following Black Friday: 47,000 concurrent users — 9× the previous peak — with zero incidents. Revenue tripled in 18 months. Checkout time fell from 94 seconds to 38 seconds.
Technologies Used
React.js
Node.js
PostgreSQL
Redis
Elasticsearch
AWS EKS
Stripe Connect