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GA4 Setup

Integrate Google Analytics 4 (GA4) with your FastSpring popup, embedded, or web checkout to track purchases and conversion events.

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If you use Google Tag Manager to manage GA4, do not set up a separate GA4 integration. Follow the Google Tag Manager guide instead.

Prerequisites

Before setting up the integration, complete the following:

  1. Create a Google Analytics account and copy your Measurement ID.
  2. Add the GA4 snippet to your website following Google's setup documentation.
  3. If you use a popup or embedded checkout, review cross-domain tracking before proceeding.

Set up the integration

Cross-domain tracking

Cross-domain tracking ensures that customer sessions are correctly attributed across your site and the FastSpring checkout. Configuration varies by checkout type.

Web checkouts

Enable cross-domain measurement in Google Analytics to prevent Outbound Click events from breaking the session when a customer navigates to the FastSpring checkout.

  1. In your Google Analytics account, go to Admin > Data Streams.
  2. Select the data stream you want to modify.
  3. Under the Google tag section, click Configure tag settings.
  4. Under Settings, select Configure your domains.
  5. Add a new row with the following values:
    • Match type: Contains
    • Domain: onfastspring.com
  6. Repeat to also add paypal.com.

GA4 cross-domain configuration

Popup and embedded checkouts

When using the Store Builder Library (SBL) for popup or embedded checkouts, include the data-decorate-callback attribute in your FastSpring script tag to pass GA4 session data through the checkout.

1. Add the attribute to your FastSpring script:

<script
  id="fsc-api"
  src="https://d1f8f9xcsvx3ha.cloudfront.net/sbl/0.9.2/fastspring-builder.min.js"
  type="text/javascript"
  data-storefront="yourexamplestore.onfastspring.com/popup-yourexamplestore"
  data-decorate-callback="decorateURL">
</script>

2. Add the following function to your page, replacing <MEASUREMENT_ID> with your own:

function decorateURL(url) {
  window.clsid = {
    client_id: '',
    session_id: ''
  };
  gtag('get', '<MEASUREMENT_ID>', 'client_id', function(r) {
    window.clsid.client_id = r;
  });
  gtag('get', '<MEASUREMENT_ID>', 'session_id', function(r) {
    window.clsid.session_id = r;
  });
  var _pl = '&clientId=' + window.clsid.client_id + '&sessionId=' + window.clsid.session_id;
  return url + '?' + _pl;
}

Troubleshooting

If you're seeing data discrepancies or missing events, use the following resources:

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Ad-blocking tools can prevent up to 10–15% of transactions from being reported. Absolute metrics like visitors and pageviews are affected, but relative metrics like conversion rates remain accurate. For server-side tracking that bypasses ad blockers, see Google Measurement Protocol.