Back in stock notifications on Shopify: with an app, without one, or not at all

When a variant that tracks inventory reaches zero, your theme shows it as sold out and switches off the buy button. That’s all. The shopper has nothing to do on the page, so they leave, and you have no record that they wanted it.

Shopify Flow does have a Product variant back in stock trigger. It’s meant for jobs inside your store, such as publishing a product again when stock returns. It doesn’t know which shoppers were waiting, so by itself it can’t tell them.

These aren’t exclusive. Plenty of stores take preorders on the products with a firm delivery date and collect emails on the rest.

You need three things: a way to collect the email, a record of what each person wanted, and a way to email them when it’s back.

1. Add a form to the product page. Shopify Forms or your theme’s contact form will do. Ask for an email address, and make sure the form records which product the shopper was looking at.
2. Ask for the size or color too. A form that only records the product can’t tell you whether someone wanted the medium or the large.
3. Say what they’re signing up for. “Email me when this is back” is permission for that one email. It isn’t permission to add them to your newsletter.
4. Keep the list somewhere you’ll check. A spreadsheet with one row per person, product and variant is enough.
5. Email them when you restock. Send it the same day. If you wait, the stock may be gone before they read it.
6. Take people off the list once you’ve emailed them, and when they ask you to stop.

The catch is the middle step. Merchants who try to automate it with Shopify Flow run into the same wall: Flow can see that a variant is back, but it can’t match each signup to that variant and email that person without extra tools or custom code. So the matching stays with you.

Each variant in Shopify has a Continue selling when out of stock setting in its Inventory section. With it on, shoppers can buy at zero stock. Shopify lists “You have stock coming soon and you want to continue selling before it arrives” as one reason to use it.

It’s the better choice when you’ve ordered the stock and can give a date. It’s the worse one when you don’t know if or when the product returns, because you’ve taken money for something you may not be able to send.

Be clear on the page. With that setting on, your product page looks exactly like an in-stock one unless you say otherwise. Add a line about when it ships, or use a preorder so the shopper sees it before they pay.