Tech Stack

• Next.js 16 & TypeScript
• PHP REST APIs
• MySQL (three databases across two retail locations)
• NextAuth, custom-bridged to legacy ZenCart auth
• JWT session tokens & HMAC order tracking
• PayPal Express Checkout & direct credit card processing
• PM2 on a VPS, coordinating with PHP APIs on shared hosting

Features

• Unified ordering system with multi-location cart splitting, cross-store inventory, and dual-database order placement
• 4-step checkout supporting PayPal Express Checkout, direct credit card processing, guest checkout, and multi-location order splitting
• Guest checkout with JWT-based session tokens, HMAC order tracking, and automatic cart merging on account creation
• Unified authentication layer bridging NextAuth with two legacy ZenCart customer databases
• SEO-preserving migration via middleware-based 301 redirects for legacy URLs and dynamic sitemap generation across two product databases
• 30+ React components, including a multi-image product gallery, responsive carousel, real-time search with filters, and reusable address/payment forms
• Structured request-ID-based logging across TypeScript and PHP layers with an admin log viewer for production debugging

Impact

• Nearly doubled online sales by consolidating two legacy storefronts into a single modern platform
• Independently identified bottlenecks in the existing sites and built the case to gain leadership approval for the rebuild
• Migrated all information, data, and assets from both legacy sites with zero downtime
• Conducted a full-stack security audit and remediated 7 vulnerabilities, including CORS misconfiguration, SSRF, and PHP Object Injection, across payment processing endpoints

What I Learned

This project taught me how to own a production system end-to-end, from proposing the rebuild to leadership through deployment and ongoing maintenance. I learned how to bridge modern and legacy infrastructure without breaking existing payment processing or admin workflows, how to reason about security across a full stack under real payment traffic, and how to break down a large, monolithic checkout flow into a maintainable, modular architecture.