Privacy Policy

1. Who we are

ZS PreSell & Back In Stock ("the app") is made by Zilancer LLC. This policy covers the data the app handles for Shopify merchants who install it and for shoppers who use it on those merchants' stores. It does not cover this website's own visitor statistics, which are described in our Cookie Policy.

2. Information we collect

From the merchant's store, through Shopify's APIs:

The store's domain, name and contact email (to run the app and send a one-time welcome email after install).
The access token Shopify issues to the app, and the store's subscription plan with the app.
Products and variants you add to campaigns — titles, handles, stock levels — and the campaign settings you save.

From shoppers, only when they choose to use a Notify me form:

Their email address, the product (and size or color, if they picked one) they asked about, and the storefront language they signed up in.
Whether they clicked the button in their back-in-stock email (the time of the first click only), so the merchant can see how many shoppers came back.

The app does not read or store shoppers' names, addresses, phone numbers or payment details. Pre-orders are placed through Shopify's own checkout.

3. How we use it

To show pre-order, coming soon and notify me campaigns on the merchant's storefront.
To create Shopify pre-order selling plans and to switch "continue selling when out of stock" on and off for campaign products.
To send a shopper one back-in-stock email, in their language, when the product they asked about comes back in stock, or when the merchant sends it from the app. The merchant can turn the automatic email off.
To send the merchant one welcome email after install, and to answer support requests.

We do not use this data for advertising and we do not sell or rent it.

4. Service providers

We use these processors to run the app:

Shopify — the platform the app runs on, including billing.
Fly.io — application hosting (United States).
Supabase — managed PostgreSQL database for campaigns, sessions and notify signups.
Resend — delivery of back-in-stock and welcome emails.

Only if the merchant turns them on, the app also passes waitlist activity (the shopper's email address and the product) to tools the merchant runs:

Klaviyo — when the merchant connects their own Klaviyo account, signups and sent back-in-stock emails are recorded as events on the shopper's profile in that account.
Shopify Flow — the merchant's own workflows receive the signup, back-in-stock and pre-order-ended events.
ZS Wishlist (also by Zilancer) — when a store uses both apps, the storefront tells ZS Wishlist that a shopper joined the waitlist, so they receive one back-in-stock email instead of two.

5. Data retention

A shopper's notify email is deleted 90 days after the back-in-stock email is sent, or after 365 days if it is never sent.
When a merchant uninstalls the app, Shopify asks us to erase that store's data 48 hours later; we then delete its campaigns, notify signups, sessions and contact record.

6. Your rights

We handle Shopify's data request and redaction webhooks automatically, so shoppers can ask the merchant for their data or its deletion through Shopify. Merchants and shoppers can also write to contact@zilancer.com to access, correct or delete their data, and we will respond within 30 days.

7. Security

Data is sent over HTTPS, database access needs credentials that only the app holds, and access is limited to the people who maintain the app. Storefront requests are verified with Shopify's app proxy signature.

8. Cookies

The app itself sets no tracking cookies on the merchant's storefront. Inside the Shopify admin, it relies on Shopify's own session handling.

9. Changes to this policy

If we change how the app handles data we will update this page and its date. Last updated: October 28, 2026.

10. Contact Information

ZS PreSell & Back In Stock
Powered by Zilancer LLC

Email: contact@zilancer.com