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About this project
Jersium is a B2C e-commerce platform built for sports jersey collectors and enthusiasts across Poland and Europe. It provides a seamless shopping experience from product discovery to secure checkout, while giving the store owner full control through a custom admin dashboard. The platform is designed for high availability, handling thousands of daily orders with sub-second page loads.
5,000+
Monthly Orders
99.9%
Uptime
< 1s
Page Speed
3 langs
Locales
Key Responsibilities
- 1Architected the full-stack solution using Laravel (API) and Next.js (storefront) with TypeScript throughout.
- 2Built product catalog management with category filters, search, and variant support (size, team, edition).
- 3Integrated Stripe Checkout with webhook handlers for order fulfilment and refund flows.
- 4Developed a custom admin dashboard for inventory, order lifecycle, and shipping label generation.
- 5Implemented multi-language support (EN, PL, DE) using next-intl with locale-aware SEO metadata.
- 6Optimised Core Web Vitals: achieved LCP < 1 s and CLS < 0.05 on mobile via image lazy-loading and ISR.
Challenges
Inventory race conditions during flash sales
Concurrent checkout requests caused overselling on limited-edition jerseys. Solved with Redis-based optimistic locking and a queue-backed reservation system that holds stock for 10 minutes during checkout.
Multi-currency + VAT for EU markets
Each EU country has different VAT rules. Built a configurable tax engine on the backend that resolves the correct rate based on the customer's billing country at cart level, with Stripe Tax for compliance.
SEO for thousands of product pages
Needed unique, crawlable URLs for every SKU variant without duplicating content. Used Next.js ISR with dynamic canonical tags and a sitemap generator that runs nightly.
Accomplishments
- Reduced checkout abandonment by 22% after redesigning the cart flow with a single-page checkout experience.
- Cut server costs by 35% by migrating product image delivery to a CDN with on-the-fly resizing.
- Achieved a 4.8/5 app store rating (Play Store listing for companion mobile app).
- Delivered the full platform in 3 months as a solo full-stack developer.
- Date
- January 2024
- Country
- 🇵🇱Poland
- Sector
- Sport
Tech Stack
LaravelNext.jsReact.jsTypeScriptTailwind CSSi8n