STOQ is a back-in-stock and preorder app for Shopify stores. It lets shoppers sign up to be notified when a sold-out product returns or when a preorder is confirmed.

By connecting STOQ to Postscript, your restock alerts and preorder confirmations are sent through your existing Postscript account—keeping all your messaging, compliance, and subscriber management in one place.

With the STOQ integration, you can:

Send back-in-stock and preorder SMS alerts through Postscript instead of a separate SMS tool.
Sync STOQ signups into a Postscript keyword so they're managed alongside the rest of your subscribers.
Build and personalize the alert messages using Postscript Automations and STOQ event properties.

In this article, we'll walk you through how to set up your STOQ x Postscript integration.

Generate Postscript Credentials

To connect the two apps, you'll first need to generate an API key and a dedicated keyword in Postscript.

Create a Postscript API Key

Select your Shop Name in the side menu of your Postscript dashboard, then select API.
Select Create Security Key Pair in the top-right corner, then confirm your action.
Select Show in the Private Key column to reveal your key, then copy it. You'll paste this into STOQ next.

Create a Postscript Keyword

Select Acquisition in the side menu of your Postscript dashboard, then select Keywords.
Select Create Keyword in the top-right corner of the page.
Name your keyword. Aim for something that will allow you to easily identify that this keyword is associated with your integration.
Select Save Keyword.
You can customize your keyword reply and add additional actions via + Add Action if desired.
Be sure to activate your keyword before going live with the integration.

Connect Postscript to STOQ

Next, you'll plug your credentials into STOQ and send "test events" to Postscript. These test events act as a ping to let Postscript know the integration is active, unlocking the triggers you'll need to build your automations later.

Configure the Integration

Open your STOQ app and go to Back in stock alerts in the sidebar menu.
Open the Settings tab, select the Notifications section, and select Customize SMS on the notification template you want to configure
In the Send SMS through panel, select the Postscript radio button.
In the Connect Postscript section, paste your Postscript private key into the Private key field, then click Verify & connect. (A green checkmark appears next to the field when the key is valid.)
Choose a keyword from the dropdown in the Select a keyword section. The keyword saves automatically when you select it.
1. If your keyword doesn't appear, click Refresh to reload the list.

Fire Test Events

While you are still in STOQ, you need to fire test events for the notifications you plan to use:

For Back in Stock: Click Send test event right below your keyword settings. This registers the back_in_stock_sms_alert trigger in Postscript.
For Preorders: Go to Preorders > Notifications > Customize SMS. Click Send test event for the preorder template. This registers the preorder_sms_confirmed trigger in Postscript.

Create Your Automations in Postscript

Now that your test events have been fired, you can build the actual messages in Postscript.

Navigate to Automations under Messaging in your Postscript account.
Select Create Automation. Choose either option, then select any of the triggers that begin with postscript-stoq.
Add a Message block and customize your copy.
1. TIP: Check out the STOQ Triggers and STOQ Tags sections below to see how you can personalize your message with dynamic properties like product names and purchase links!
Activate your flow.
Return to STOQ and click I've created the Flow to confirm the setup.

TIP: We recommend creating two separate flows—one for back-in-stock alerts and one for preorder confirmations—so you can tailor the message content specifically for each scenario.

Test Your Setup

With the flow live, run an end-to-end test to confirm everything works:

Visit your storefront and sign up for a back-in-stock alert using your phone number.
Confirm the opt-in SMS from Postscript by replying Y.
Restock the product in Shopify, or go to STOQ > Reports > Current waitlist and click Send.
Check your phone for the back-in-stock SMS alert delivered through Postscript.

If the alert doesn't arrive, see the Troubleshooting section below.

Preorder Notifications

The integration also works for preorder SMS confirmations. The SMS provider setting is shared across notification types, so if you already selected Postscript for back-in-stock alerts, it also applies to preorder notifications.

To configure the preorder flow:

In STOQ, go to Preorders > Notifications > Customize SMS.
Click Send test event for the preorder template to register the preorder trigger (preorder_sms_confirmed). This is a separate event from the back-in-stock trigger.
Create a second automation in Postscript triggered by preorder_sms_confirmed, add a Message block with your preorder confirmation, and activate it.

Tip: Keep separate flows for back-in-stock alerts and preorder confirmations so you can tailor the message content for each scenario.

STOQ Triggers

The STOQ × Postscript integration works by sending triggers to Postscript when a key event happens.

In the Postscript Automation builder, these appear prefixed with postscript-stoq - (for example, postscript-stoq - back_in_stock_sms_alert). You can use these triggers to build Automation Flows inside the Postscript admin based on the events below.

NOTE: The Potential SMS Example column shows example copy your shop could send for each trigger.

Trigger	Description	Potential SMS Example
`back_in_stock_sms_alert`	Sent when a customer's waitlisted product is back in stock.	Good news {customer_name}! {product_title} is back in stock at {shop_name}. Grab it here: {purchase_link}
`back_in_stock_sms_reminder`	Sent as a follow-up reminder to a customer who was alerted but hasn't purchased yet.	Reminder {customer_name}: {product_title} is still in stock at {shop_name}, but going fast. Grab it here: {purchase_link}
`preorder_sms_confirmed`	Sent when a customer's preorder is confirmed.	Thanks {customer_name}! Your preorder of {first_product} is confirmed and is expected to ship {shipping_timeline}.

STOQ Tags

When STOQ fires an event to Postscript, it includes properties you can use to personalize your SMS in the Postscript message editor.

The available properties depend on the event type.

NOTE: Back-in-stock alerts and reminders share the same tag set.

Back-in-stock tags

Tag	Definition
`product_title`	Product name
`variant_title`	Variant name (e.g., "Medium / Blue")
`title_incl_variant`	Full product name including variant
`vendor`	Product vendor
`price`	Product price
`currency`	Price currency code (e.g., "USD")
`purchase_link`	Direct link to buy the product
`image_url`	Product image URL
`shop_name`	Your store name
`customer_name`	Customer's name
`customer_phone`	Customer's phone number

Preorder tags

Tag	Definition
`order_name`	Order number (e.g., "#1001")
`products`	Comma-separated list of preorder products
`first_product`	Name of the first preorder product
`products_count`	Total number of preorder products
`shipping_timeline`	Expected shipping date
`shop_name`	Your store name
`customer_name`	Customer's name

Troubleshooting

Symptom	Likely cause	Fix
"Invalid Postscript API key" error when verifying	The private key is incorrect or expired	Generate a new Security Key Pair under Settings > API in Postscript and paste the new private key into STOQ.
No keywords appear in the dropdown	No keywords have been created in Postscript	Create a keyword under Acquisition > Keywords in Postscript, then click Refresh in STOQ.
Test event sent but flow doesn't trigger	The flow trigger doesn't match the STOQ event type	Confirm your flow's trigger is set to the exact event name shown in STOQ (e.g., `back_in_stock_sms_alert`)
Customer signed up but didn't receive SMS	Customer hasn't confirmed opt-in	The customer must reply Y to the Postscript opt-in message before they can receive alerts.
SMS works for back-in-stock but not preorder	Preorder flow not created or not active	Create a separate flow triggered by `preorder_sms_confirmed` and make sure it's activated.
"Postscript rate limit exceeded" error	Too many API calls sent in a short window	Wait and retry. If restocking many products at once, space them out to stay within Postscript's rate limits.
Setup appears incomplete (missing green checkmarks)	One or more setup steps were skipped	Open the Send SMS through panel and complete each step that doesn't show a green checkmark.

Get Support

Have questions? Please feel free to reach out to our Support team at [email protected] or via live chat.

For help with STOQ-specific settings, contact the STOQ team at [email protected].

Set Up Your STOQ Integration