Stop losing customers when products sell out. Appfox captures demand with automated "Notify Me" buttons and pre-order capabilities. Accept partial payments for out-of-stock items, send smart email/SMS alerts when inventory returns, and track which products customers want most. Works with all Shopify themes and integrates with Klaviyo, Mailchimp, and other marketing tools. Built for serious merchants who want to maximize revenue from every product, whether in stock or not.