PaySlot — Mobile-First Booking Engine & Paystack Storefront PWA

A commercial, mobile-first appointment booking engine and storefront engineered by David Erikefe (davebuiltit). Built as Project 2 of our Senior Frontend Engineering Blueprint.

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⚡ Key Engineering Highlights

1. Fintech Transaction Integrity:
   • Demonstrates why client-side prices are never trusted.
   • Built-in Paystack Webhook Inspector illustrating server-side cryptographic signature validation (x-paystack-signature via crypto.createHmac('sha512', secret)).
2. Atomic Slot Lockout:
   • Prevents booking collisions and calendar race conditions.
   • Confirmed appointments lock the time slot dynamically with real-time UI state updates.
3. Offline PWA Resilience:
   • Caches transaction receipts and appointment confirmation passes in local device storage for offline access.
4. Mobile-First Ergonomics:
   • Engineered for one-thumb mobile workflows with $\ge 44\text{px}$ touch targets and zero rubber-band bounces.

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🚀 Quick Start

Double-click index.html in any browser, or run:

npx serve .

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👨‍💻 Author

David Erikefe (davebuiltit)

• Portfolio: daviderikefe.vercel.app
• Research: Accepted Author at ICMLDE 2026
• GitHub: @erikefedavid