> ## Documentation Index
> Fetch the complete documentation index at: https://docs.upstackdata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# subscribe Event

> Track when a visitor subscribes to email or SMS marketing

Fires when a visitor subscribes to email or SMS marketing. This helps track marketing list growth and attribute new subscribers to campaigns.

<Note>
  **Shopify:** Tracked via popup/form hooks when using compatible email/SMS apps. Manual implementation may be required for custom forms.
</Note>

## JavaScript

```javascript theme={null}
window._upstack('track', 'subscribe', {
  channel: 'email',
  source: 'footer_form',
  value: 5.00,
  currency: 'USD'
});
```

SMS subscription:

```javascript theme={null}
window._upstack('track', 'subscribe', {
  channel: 'sms',
  source: 'popup',
  phone: '+15551234567'
});
```

## Properties

| Property | Type   | Required | Description                                                     |
| -------- | ------ | -------- | --------------------------------------------------------------- |
| channel  | string | No       | Subscription channel (`'email'`, `'sms'`, `'push'`)             |
| source   | string | No       | Subscription source (e.g., `'popup'`, `'footer'`, `'checkout'`) |
| value    | number | No       | Estimated subscriber value                                      |
| currency | string | No       | ISO 4217 currency code                                          |

## When to Fire

* Newsletter signup
* SMS opt-in
* Push notification subscription

## Related Events

* [lead](/pixel/events/lead) — For general lead capture
* [complete\_registration](/pixel/events/complete-registration) — For account creation