User ID power-up

The User ID power-up generates a persistent, privacy-friendly identifier and appends it to every request processed by your sGTM container. It works by hashing non-personally identifiable signals (user IP, user-agent string, hostname, and TLS settings) into a stable user ID that helps maintain tracking continuity even when cookies and cross-domain tracking are restricted. This generic identifier is attached to all incoming requests through the X-Stape-User-Id header. Because it operates exclusively within server-container request headers, it’s never saved as a browser cookie or used to identify specific individuals.

The identifier remains persistent across browser sessions even after closing the browser, as long as the signals (IP address, user-agent, TLS settings, and hostname) remain unchanged. The power-up evaluates IPv6 signals when supported by the user's provider, defaulting to IPv4 otherwise.

User ID is available on the Free subscription plan and higher.

1. Log in to your Stape account and select your sGTM container from the dashboard.

2. Go to Power-ups and click Use next to the User ID panel.

3. Toggle the User ID switch to enable it and click Save changes.

4. Go to your sGTM container in Google Tag Manager.

5. Click Variables and click New.

6. Set the variable type to Request Header.

7. Give the variable the X-Stape-User-Id name and click Save.

1. 1.
   Open Preview in the sGTM container.
2. 2.
   Go to the Requests tab, and inspect an Incoming HTTP Request from your site. 
3. 3.
   You should see X-Stape-User-Id listed under Request Headers, confirming the power-up is active.

A sample scenario is an eCommerce store that relies on remarketing campaigns to re-engage users. Their campaigns show strong reach metrics, but audience sizes are smaller than expected and frequency is inconsistent, because a large share of returning visitors are unrecognized across sessions, they fall out of remarketing pools and are never re-engaged.

You can identify this problem and fix it this way:

1. 1.
   In Google Ads, compare your remarketing audience sizes against your actual returning visitor volume from GA4 for the same period. If your audience within the last 30 days is significantly smaller than the returning users count in GA4, cookie loss is preventing consistent user recognition.
2. 2.
   Enable the User ID power-up and create a Request Header variable in sGTM with the Header Name X-Stape-User-Id.
3. 3.
   Monitor your remarketing audience sizes over the following 2-4 weeks and compare them against the baseline period.

If cookie blocks were previously causing returning visitors to be dropped from audiences, you should see remarketing pool sizes grow as the hashed identifier allows the same users to be consistently recognized across sessions.