I built the platform with Next.js, React, TypeScript, PostgreSQL, Drizzle ORM, Stripe, Tailwind CSS, and Jest. Verified Stripe webhooks are the source of truth for payments, while database transactions and idempotency controls prevent duplicate payment attempts and orders. Item-level state management supports partial fulfillment and automatic wallet credits when a service fails. I also implemented JWT authentication, role-based access, email verification, password recovery, rate limiting, localization, responsive interfaces, and automated tests for the main purchase flow and edge cases.