⚠️ Before you start
This feature is only available for Shopify Plus customers and needs to be enabled by our team before it becomes visible in charles. If you're interested, please contact our support team and we will activate this section for you.
How it works
What is the advantage to using the Checkout Page?
The Checkout Page widget has a distinct advantage over the Thank You Page: it's embedded directly within the payment journey, so it can be configured to block checkout from proceeding until the customer enters a valid phone number. This ensures only valid numbers are collected, giving you greater control over data quality. You can also choose whether the opt-in checkbox is preselected by default.
The checkout widget UI can be placed anywhere on the Checkout Page with widget adapting automatically per the information entered by the customer.
Phone number already entered — the widget will not display a phone number field, as it has already been captured
Email address only entered — the widget will display a phone number field so the customer can provide their number
Single or Double Opt-In
By default, the checkout widget uses single opt-in — the customer simply checks a box to indicate they would like to receive communications via WhatsApp.
Alternatively, the widget can be configured to use double opt-in via a one-time passcode (OTP). When enabled, the customer receives a 6-digit code via WhatsApp and must enter it correctly to complete their subscription.
The OTP feature must be enabled by our team on the backend. While the feature itself is free, please note that each verification message sent to a customer may incur an authentication fee charged by Meta.
Please contact support if you would like to activate OTP or double opt-in functionality on your checkout page.
Configuring the Checkout Page
Prerequisites
A Shopify Plus subscription
The Checkout Page feature enabled on your universe
The OTP feature enabled on your universe (required only if you wish to configure double opt-in at checkout)
Create a checkout page subscription: Go to Audiences → Subscriptions and create a new subscription. We recommend creating a dedicated subscription specifically for the Shopify Checkout Page to make tracking easier.
If you would like to attach OTP functionality, please ensure the subscription type is set to "Double Opt-in".
Configure Checkout Page in Charles: Navigate to Automation → Checkout Page and click "Create New" to set up a new checkout page, or "Edit" to modify an existing one.
Please note that only single opt-in subscriptions will be displayed if the OTP (double opt-in) feature has not been enabled for your universe. Once enabled, double opt-in subscriptions will also become available, and a Verification Code section will appear on the configuration page.
You can also configure your messages and set your desired languages from this page. Don't forget to hit save.
Configure Checkout UI Widget In Shopify: In Shopify, navigate to Settings → Checkout and click "Edit". Click on "Apps" and select the Checkout UI from Charles. Click the "+" button to add the widget to your checkout page — you can place it in either the Main or Order Summary section.
Once the block has been added, two additional options become available in the Checkout Behavior panel:
Allow app to block checkout — When enabled, the checkout will not proceed if the customer enters an invalid phone number, ensuring only valid numbers are collected.
Include block in Shop Pay — When enabled, the widget also appears for customers checking out via Shop Pay
Preview Checkout UI Widget: In Shopify, navigate to Settings → Checkout. Under Configurations, click "Edit". At the top of the editor, use the dropdown to select the Checkout page. Click the three horizontal dots button (⋯) (second from the right) and select "View" to preview how the Checkout UI widget on the Checkout Page will appear to customers.
Points to Consider
Using Both the Checkout Page and Thank You Page: If you have both the Checkout Page and Thank You Page configured, visitors may encounter the opt-in widget at two separate points in their journey. This is intentional — each widget is designed to handle a different stage of the purchase journey.
When to use both: Using both increases the likelihood of capturing a subscription, as customers have two opportunities to opt in — once during checkout and once after completing their purchase.
When to use only one: If you prefer to collect only a single subscription per customer, we recommend choosing one configuration only.