Holdline

Turn out-of-stock products into revenue without the risk of overselling. Holdline enforces pre-order limits natively through Shopify checkout — no fragile scripts, no leftover code. Tag orders instantly for warehouse/3PL fulfillment, and get alerted the moment stock is back so you can end pre-orders in one click. Isolated virtual inventory keeps your real warehouse counts untouched. Built on Online Store 2.0 Theme App Extensions — clean install, clean uninstall.