How to Sync STOQ Customer Data to Klaviyo

When a visitor signs up for a back-in-stock or preorder alert through STOQ, the app can automatically sync their profile to your Klaviyo account. This lets you build targeted segments, trigger flows, and run campaigns based on real purchase-intent data. You can also customize the profile tag that STOQ attaches to each synced customer so you can easily filter and identify them in Klaviyo.

Before You Begin

Make sure you have the following before you enable the Klaviyo integration:

• A paid STOQ plan (the Klaviyo sync is not available on the free plan)
• A Klaviyo account with permission to install apps and manage profiles
• STOQ is installed and active on your Shopify store

How to Connect Klaviyo and Enable Customer Sync

Follow these steps to connect your Klaviyo account and start syncing customers.

Step 1: Open the Integrations Page

1. Open the STOQ app in your Shopify admin.
2. Click Back in stock alerts in the left-hand menu.
3. Navigate to the Settings section, then scroll to Integrations.
4. Click Set up on the Klaviyo card.

Step 2: Enable the Sync Toggle

1. Turn on the Sync visitors with Klaviyo toggle.
2. Click Save in the top bar to confirm.

Once enabled, STOQ will sync every new customer who registers for a back-in-stock or preorder alert to your Klaviyo account.

Step 3: Connect Your Klaviyo Account

1. After enabling the toggle, click the Connect button under the Klaviyo app heading.
2. A new browser tab opens with the Klaviyo authorization screen.
3. Review the requested permissions and click Allow to authorize STOQ.
4. You are redirected back to the STOQ app. A green Connected badge confirms the link.

Step 4: Set Your Profile Tag

1. In the Settings section beneath the Klaviyo toggle, locate the Profile tags field.
2. Enter a tag value (for example, restock-rocket or back-in-stock-signup).
3. Click Save.

STOQ uses this tag as the $source property on every profile it syncs to Klaviyo. The default value is restock-rocket.

Understanding Customer Properties Synced to Klaviyo

STOQ syncs detailed profile data so you can segment and personalize your Klaviyo campaigns.

Standard Profile Fields

When a customer signs up for an alert, STOQ creates or updates their Klaviyo profile with:

• Email and/or Phone number (depending on the channel they used to sign up)
• First name and Last name (parsed from the customer name, if provided)
• Locale (the language of the storefront they used)
• Location (country based on their signup)

Custom Profile Properties

STOQ also attaches custom properties to each Klaviyo profile. You can use these to build segments and flow filters.

Metrics Sent to Klaviyo

In addition to profile data, STOQ automatically sends a Customer signed up for alert (STOQ) metric event to Klaviyo every time a customer registers for an alert. This event includes:

• Product details (title, variant, handle, vendor, image URL)
• Customer details (name, email, phone, country)
• Signup context (channels used, signup timestamp, shop name)

You can use this metric to create Klaviyo flows (for example, a welcome sequence for new alert subscribers).

Double Opt-In Settings in Klaviyo

Klaviyo's double opt-in setting affects how quickly synced customers appear as subscribed profiles.

• Double opt-in enabled (Klaviyo default): Customers receive a confirmation email from Klaviyo after STOQ syncs their profile. They must click the confirmation link before Klaviyo marks them as subscribed.
• Double opt-in disabled: Customers are subscribed immediately when STOQ syncs their profile. No confirmation email is sent.

Known Limitations

There are a few constraints to keep in mind when using the Klaviyo sync.

• The Klaviyo integration requires a paid STOQ plan. Free-plan stores cannot enable it.
• STOQ syncs customers one at a time as they sign up. There is no bulk retroactive sync for customers who signed up before you enabled the integration.
• The profile tag field is shared across all marketing integrations. You cannot set a different tag for Klaviyo and Shopify independently.
• If a customer signs up with both email and phone, and those belong to separate existing Klaviyo profiles, STOQ updates both profiles independently.
• STOQ requires at least an email or phone number to sync a customer. Anonymous visitors without contact information are not synced.

Troubleshooting

If you run into issues with the Klaviyo sync, check the table below.

FAQs

Q : What is the $source property in Klaviyo?

A : The $source property tells you where a Klaviyo profile originated. When STOQ syncs a customer, it sets $source to the value of your Profile tags field (default: restock-rocket). You can use this property to create segments of customers who came through STOQ.

Q : Can I change the profile tag after I have already synced customers?

A : Yes. Go to the Integrations page, update the Profile tags field, and click Save. New signups will use the updated tag. Previously synced profiles keep the old tag value in Klaviyo.

Q : Does STOQ sync existing customers when I first enable the integration?

A : No. STOQ only syncs customers going forward from the moment you enable the integration. Customers who signed up before the integration was turned on are not retroactively synced to Klaviyo.

Q : Can I use Klaviyo to send back-in-stock alert emails instead of STOQ?

A : Yes, but that is a separate feature. To send alerts through Klaviyo, go to Back in stock alerts > Notifications > Customize and select Klaviyo as your email or SMS provider. This article covers only the customer profile sync.

Q : Do I need a Klaviyo Private API key?

A : No. STOQ uses OAuth to connect to Klaviyo, which is more secure and does not require you to copy-paste API keys. If you previously used a Private API key, STOQ will prompt you to switch to the OAuth connection.

Q : Will disabling the sync toggle remove my customers from Klaviyo?

A : No. Turning off the sync toggle only stops new customers from being synced. Profiles already in Klaviyo remain untouched.

Updated on: 14/04/2026