Promo Code System & Cloudflare Turnstile CAPTCHA for a Next.js E-commerce Site

Built two features into an existing Next.js e-commerce platform: an admin-managed discount code system and site-wide spam protection. The promo code system lets the store owner create and manage discount codes from the admin panel — percentage or fixed-amount discounts, minimum-spend thresholds, maximum-discount caps, expiry dates, and usage limits, with live redemption tracking. At checkout, customers enter a code and the discount is applied instantly with the total updating in real time. Every code is re-validated on the server before an order is placed, and card payments (via Stripe) are automatically charged the correct discounted amount, so totals can't be tampered with from the browser. For spam protection, Cloudflare Turnstile was integrated across every public form on the site — contact, quote requests, chatbot, homepage popup, product enquiries, registration, and the cart — with server-side token verification on all form-handling endpoints. It was implemented with a safe, phased rollout: verification runs in monitor mode first and only starts blocking once enforced, so no legitimate form is ever broken during activation. The existing hCaptcha setup on the homepage form was migrated over to keep everything on one system. Delivered clean, type-safe, production-ready code that matches the existing architecture, with no changes to the current UI or functionality beyond the new features.