The Challenge
The existing e-commerce platform was built on legacy technology that resulted in slow page loads, poor mobile experience, and declining conversion rates. The business needed a modern, performant frontend that could scale with growing traffic.
My Role
As the Lead Frontend Engineer, I was responsible for:
- Architecting the new frontend using Next.js and TypeScript
- Leading a team of 4 frontend developers
- Establishing coding standards and review processes
- Implementing the design system
- Optimizing performance for Core Web Vitals
Technical Approach
Architecture Decisions
We chose Next.js for its excellent SSR capabilities and built-in optimization features. The app router allowed us to leverage React Server Components for improved performance.
Key architectural decisions included:
- Server Components by default - Reduced client-side JavaScript significantly
- Streaming SSR - Improved Time to First Byte (TTFB)
- Edge middleware - Handled personalization and A/B testing at the edge
- ISR - Balanced between static performance and dynamic content
State Management
We implemented a hybrid approach:
- React Query for server state (products, cart, user data)
- Redux Toolkit for complex UI state (filters, modals, checkout flow)
- URL state for shareable filters and pagination
Performance Optimizations
- Implemented image optimization with automatic WebP conversion
- Code splitting and lazy loading for below-the-fold content
- Prefetching for likely navigation paths
- Service worker for offline support and caching
Key Learnings
- Incremental migration works - We migrated page by page, which reduced risk
- Measure everything - Real user metrics were essential for prioritization
- Accessibility is not optional - We caught significant issues through automated testing
Results
The redesign resulted in measurable business impact:
- 95+ Lighthouse Performance score (up from 55)
- 23% increase in conversion rate
- 60% reduction in page load time
- 40% reduction in bounce rate