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 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.

Since hostname is part of the hash, the same user gets a different X-Stape-User-Id on each domain. If your users move between several domains (for example, from your main website to a checkout on a separate domain), you can also enable the Cross-domain ID option. It adds an additional X-Stape-Cross-Domain-Id header, generated from the same signals except hostname, so the same user gets one ID across all domains that send requests to your sGTM container. The standard X-Stape-User-Id keeps working as before.

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 , scroll down to the Data enrichment section, and click on 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.

8. If you enabled Cross-domain ID, repeat steps 5–7 to create another Request Header variable with the X-Stape-Cross-Domain-Id name.

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. If you enabled Cross-domain ID, you should also see X-Stape-Cross-Domain-Id.

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.