E-Commerce implementation checklist

Verify all product images are served via a CDN like Cloudinary or Vercel Image Optimization in WebP/AVIF formats with correct 'sizes' attributes.

Ensure the primary product image on PDPs (Product Detail Pages) uses the 'priority' attribute and is not lazy-loaded.

Implement stale-while-revalidate or Incremental Static Regeneration (ISR) for product listings to keep TTFB under 200ms.

Apply 'font-display: swap' and pre-connect to font origins to prevent layout shifts during text rendering.

Run a production build analysis to ensure third-party scripts (chat widgets, tracking) do not exceed 50KB of main-thread execution time.

Implement idempotent webhook handlers for Stripe or Adyen to prevent duplicate order creation on network retries.

Verify that tax calculation services (Stripe Tax or Avalara) trigger correctly based on the shipping address before the final payment intent.

Ensure inventory is reserved or deducted atomically during the checkout flow to prevent overselling during high-traffic events.

Validate that the price displayed in the cart matches the currency and amount sent to the payment provider across all regions.

Test the end-to-end flow for non-authenticated users to ensure session persistence from cart to 'thank you' page.

Configure automated triggers to update Algolia or Meilisearch indexes immediately when product status or stock changes in the CMS.

Verify that category filters (size, color, price) update the product grid without a full page reload and maintain URL state.

Implement a 'No results found' state that provides alternative product recommendations to reduce bounce rates.

Audit AI-generated product descriptions for duplicate content patterns to avoid SEO cannibalization across similar SKUs.

Ensure that selecting a variant (e.g., XL size) updates the SKU, price, and image gallery immediately.

Inject valid Schema.org markup including price, availability, aggregateRating, and brand on all PDPs.

Verify that variant URLs or filtered category pages point to the primary canonical URL to prevent duplicate content issues.

Configure a dynamic sitemap.xml that includes all active product, category, and CMS pages, updated at least daily.

Disallow crawling of sensitive or low-value routes like /cart, /checkout, and /account/ search result pages.

Generate dynamic social sharing images for products that include the product name, price, and primary image.

Confirm that no raw credit card data touches your server and that all inputs use hosted fields or elements from the payment provider.

Ensure public API keys (Algolia, Stripe Publishable) are restricted by domain and have minimal required permissions.

Implement rate limiting on the 'Add to Cart', 'Login', and 'Checkout' endpoints to prevent bot-driven inventory locking.

Validate and sanitize all review submissions and contact forms to prevent XSS and injection attacks.

Implement a consent management platform that blocks tracking scripts until the user provides explicit permission.

Set up alerts in Sentry or Datadog for payment intent failures to identify issues with specific regions or card types.

Implement automatic redirects for discontinued product URLs to the most relevant parent category.

Verify that abandoned cart events are correctly sent to the marketing automation platform (Klaviyo/Mailchimp) after 30 minutes of inactivity.

Deploy RUM tracking to capture actual Core Web Vitals from users across different device types and network speeds.

Ensure the 'Add to Cart' button is disabled and replaced with a 'Notify Me' or 'Out of Stock' label when inventory reaches zero.