E-Commerce Platform Rebuild
A ground-up rebuild of a high-traffic e-commerce platform that dramatically improved conversion rates, reduced infrastructure costs, and scaled to handle 10x the original traffic.
Challenge
A mid-market fashion retailer was running on a monolithic Rails application built in 2016. The platform was struggling under the weight of flash sales — page load times routinely hit 8–12 seconds during peak traffic, cart abandonment was above 70%, and the engineering team spent more time on firefighting than features. The client needed a modern platform that could scale, perform, and support rapid experimentation without engineering bottlenecks.
Solution
We proposed a decoupled architecture: a React frontend on the edge, a Node.js API layer with horizontal scaling, and PostgreSQL with read replicas for the data tier. The migration was phased over six months — starting with the storefront and product catalogue, then checkout, then the admin tools — so the business never had to go dark.
We introduced a feature flag system from day one, which let the client run A/B tests across checkout flows, product page layouts, and promotional banners without engineering involvement. This alone materially changed how the product and marketing teams operated.
Technical Approach
The frontend was built with React and deployed to Cloudfront via a CI/CD pipeline on GitHub Actions. We used server-side rendering for product and category pages for SEO, and client-side hydration for cart and checkout to keep interactions snappy.
The API layer used Node.js with Express, broken into domain services: catalogue, inventory, orders, and users. Each service connected to PostgreSQL through a connection pool, with Redis used for session state and catalogue caching. Write operations went to the primary; all reads hit read replicas.
Infrastructure lived on AWS — ECS Fargate for the API services, RDS for PostgreSQL, ElastiCache for Redis, and CloudFront for edge delivery. We used Terraform for all infra-as-code, which meant the client inherited reproducible, version-controlled infrastructure from day one.
A full automated test suite covered unit tests, integration tests, and end-to-end checkout flows via Playwright. Deployment time from merge to production was under four minutes.
Results
- 40% increase in conversion rate in the first 90 days post-launch
- Page load time dropped from 8.2s to 1.1s at the P95 for product pages
- Infrastructure costs reduced by 35% despite handling 10x peak traffic
- Cart abandonment fell from 71% to 48% following checkout UX improvements identified through A/B testing
- Zero downtime during two major flash sales in Q4, each handling over 50,000 concurrent users
- Engineering team reduced time spent on incident response from ~40% to under 10% of weekly hours
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