Checkout Rules validates cart quantities before customers complete their purchase and during admin draft order creation. You configure maximum quantities using product metafields, and the app automatically enforces these limits during checkout and when creating orders in admin. Validation works with all checkout methods including express checkout options. Customers receive clear messages when they exceed limits and must adjust quantities to proceed.

• Maximum Quantity Enforcement - Set purchase limits using product metafields
• Real-time Cart Validation - Prevents checkout when limits are exceeded
• Admin Draft Order Validation - Enforces limits in Shopify admin orders
• Custom Error Messages - Clear instructions when quantity limits reached
• Simple Metafield Setup - Configure using "custom.max_qty" fields