Available on the Free plan.

The Back in stock flow lets shoppers ask to be notified the moment a sold-out product is available again. That way, you don't lose the sale to someone who left empty-handed.

How it looks

Sold-out products show a Notify me when back in stock button. A shopper clicks it, enters their email, and joins the waitlist for that exact variant.

How it works

Use back in stock alerts to:

Capture demand you'd otherwise lose — a shopper on a sold-out variant enters their email and joins the waitlist for that exact variant.
Alert everyone the instant it restocks — when the variant is back in stock, everyone waiting on it is emailed at once.
Optionally follow up — turn on a second reminder email for shoppers who've also opted into marketing.

Considerations

The alert email sends even without marketing consent. Since the shopper explicitly asked to be notified, this first email is transactional and isn't blocked by a lack of marketing opt-in. It still includes an unsubscribe link.
The reminder email is optional and consent-gated. It's off by default, only reaches shoppers who've opted into marketing, and only sends if the item is still in stock.
In the flow builder, the restock alert stays first. The first email is the restock alert. It can't be moved or deleted, and it stays live while the flow is on. The flow builder is available only to certain stores.
One alert per signup. If the item sells out again, shoppers need to sign up again.
Running another back in stock app at the same time can cause duplicate buttons or emails. We don't detect this automatically — turn off the other app's back in stock feature if you use Judge.me's.

Set up the Back in stock flow

Step 1: Enable the Back-in-stock notify app embed

The Back-in-stock notify app embed shows the Notify me when back in stock button on sold-out products in your store. The flow can't collect sign-ups until it's on, even when the flow itself is on.

To enable the Back-in-stock notify app embed:

From your Shopify admin, go to Online Store > Themes.
Find the theme that you want to edit, and then click Edit theme.
Click the App embeds icon (the third icon) on the top left.
In the search bar, enter "Judge.me Back-in-stock notify".
Turn on the Back-in-stock notify app embed toggle.
Click Save on the top right.

Step 2: Turn on the Back in stock flow

Available on the Free plan

The steps to turn on the Back in stock flow depend on whether your store has the flow builder, which is in early access and is available only to certain stores. Most stores don't have it yet.

To turn on the Back in stock flow (for most stores):

From your Judge.me Email app, go to Flows.
Click Back in stock.
Click Activate flow.
In the confirmation window, click Activate flow.

If you don't see Activate flow at the top of the flow page, your store has the flow builder.

To turn on the Back in stock flow in the flow builder:

From your Judge.me Email app, go to Flows.
Click Back in stock.
If you have unsaved changes, click Save.
Click Turn on.
In the confirmation window, click Activate flow.

If the flow is on but the app embed is off, a banner on the flow reminds you that the button isn't showing yet.

Check the Back in stock waitlist

Available on the Free plan

Customers can join a waitlist once the flow and the app embed are both on. The waitlist shows every product with customers waiting, sorted by demand.

The steps to open the waitlist depend on whether your store has the flow builder, which is in early access and is available only to certain stores. Most stores don't have it yet.

To check who is waiting for a restock (for most stores):

From your Judge.me Email app, go to Flows.
Click Back in stock.
At the bottom of the page, click View waitlist.
Click a product to see who is waiting for it.
Optional: To narrow the list, search for a customer or select a variant.

If you don't see View waitlist at the bottom of the flow page, your store has the flow builder.

To check who is waiting for a restock in the flow builder:

From your Judge.me Email app, go to Flows.
Click Back in stock.
Click the Trigger and conditions card at the top of the flow.
Click View waitlist.
Click a product to see who is waiting for it.
Optional: To narrow the list, search for a customer or select a variant.

In the flow builder, Customize storefront button is in the same Trigger and conditions panel. To add, move or delete emails and delays, see Editing flows in the flow builder.

Customization

Button text and color — go to Settings > Back in stock > Customize button to edit the button, form, and success message copy, plus the button color and corner radius.
Newsletter opt-in checkbox — the signup form can show an unticked "Also send me news and offers" checkbox. It's on by default; turn it off in the same settings page if you don't want it. Ticking it enrolls the shopper into your marketing list through your store's normal double opt-in.
Per-product eligibility — on the Waitlist page (see Check the Back in stock waitlist above), use the toggle on a product's row to turn off new sign-ups for it. Customers already waiting are still notified when it restocks.

Troubleshooting

The "Notify me" button isn't showing on my storefront

Check that the flow is Active (Flows > Back in stock) and the app embed is turned on (Theme editor > App embeds > Back in stock) as shown in Step 1 and Step 2 — both are required. The button also only appears on variants that are actually sold out; an in-stock variant always shows the normal add-to-cart button.

I'm seeing two "Notify me" buttons, or shoppers are getting duplicate emails

This usually means another app is also handling back in stock alerts. Turn off that app's back in stock feature to avoid duplicates.

A shopper says they never got the alert email

Check if they weren't waiting on a different variant than the one that restocked — the waitlist is variant-specific.

Resources

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Judge.me Email: Back in Stock flow