How does the Thank You Page Work
Background
Prior to May 2026, customers only needed to enter their phone number on the Thank You Page (TYP) to be automatically subscribed or enrolled in flows — no further action was required. To make consent more explicit and better support GDPR compliance, we have revised the widget. The TYP now defaults to single opt-in with an explicit checkbox, requiring customers to actively confirm they wish to receive WhatsApp messages rather than being subscribed automatically.
Single or Double opt-in
The Thank You Page can be configured as either single or double opt-in.
Single opt-in is the default behaviour — the customer enters their phone number and checks a box to confirm their consent. The checkbox cannot be pre-enabled; it must be left unchecked by default.
Double opt-in can also be enabled on the Thank You Page. When activated, submitting a phone number triggers our backend to send a one-time 6-digit passcode (OTP) to the customer via WhatsApp. Because entering the code is a deliberate second action, this method is always classified as double opt-in and cannot be configured as single opt-in. The subscription is only completed once the customer enters the code correctly.
The OTP feature is free to enable on the Thank You Page and does not require a Shopify Plus subscription. Please note that each verification message sent may incur an authentication fee charged by Meta. Contact support to get it enabled.
Configuring the Thank You Page
Prerequisites
Shopify integrated with your Universe
The OTP feature enabled on your universe (required only if you wish to configure double opt-in at the end of the purchase Journey)
Add Charles Checkout UI Widget to Shopify Shop: If you were already using the Thank You page, the widget is most likely already visible in your Shopify checkout — no further setup needed. If not, follow these steps:
In Shopify, go to Settings → Checkout and click Edit on the relevant configuration.
Click Apps, then select the charles Checkout UI widget.
Use the dropdown at the top of the editor to navigate to the Thank You page.
Click the + button where you want the widget to appear, then select it from the list to add it.
Place it in either the Main or Order Summary section.
Create a Subscription to Attach to the Thank You Page: The Thank You page defaults to single opt-in. To access double opt-in subscriptions, contact support to have OTP enabled on your Universe.
Navigate to Audiences → Subscriptions → Create New.
If you're replacing or supplementing an existing single opt-in subscription, add it under "Accept general opt-ins for order flows" in Advanced Settings of the Shopify Integration. This ensures existing contacts can still be enrolled in flows.
Navigate to Automation → Thank You Page and click Create New (or Edit to modify an existing page).
Under Select Subscription, choose the opt-in you want to apply. All contacts completing the Thank You page will receive this opt-in.
Note: the Thank You Page defaults to single opt-in. The double opt-in feature must be enabled on your Universe to show double opt-in subscriptions in this dropdown.
Configure Language Settings: The checkout UI widget can render in any language, but it must match the active checkout language for that market to display correctly.
For help setting up checkout languages per market in Shopify, see Shopify's guide to managing markets.
In charles, go to Settings → General → Template Languages, select the desired languages, and save.
Return to the Thank You Page in Automations. Under Widget content, click the + icon to add a language variation.
Configure "Click to Subscribe" Button: An alternative to OTP: instead of entering a verification code, contacts click a Subscribe button on the Thank You page, routing them through a flow to complete double opt-in.
Go to Journeys, select the Thank You Page Click to Subscribe trigger, and design the flow.
💡 Tip: You can use Shopify variables — such as Gross Total, Net Total, Tax, Total Discount, Currency, Customer Locale, Custom ID, and Summary — in Condition and Messaging nodes.
On the Thank You Page configuration, toggle Click to Subscribe on. It can be used alongside the confirmation button or on its own.
Click the Click to Subscribe button to open its settings, then under Flow to trigger, select the flow you want to direct contacts into.