Custom GTM and GA4 Loader

The Custom Loader power-up minimizes the impact of ad blockers on your GTM and GA4 scripts by routing them through a path that turns all cookies into first-party cookies.

Custom Loader is available on the Free subscription plan and higher. To check your current plan or upgrade, go to your sGTM container settings.

How to set up Custom Loader

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 Custom Loader panel.

3. Toggle the Custom Loader switch to enable it and click Save changes.

4. In the Code & Setup information section, configure the following settings:

- Domain - select one of the domains linked to your container.

- Web GTM ID - enter your web Google Tag Manager ID.

- Enhanced ad blocker protection - when enabled, all requests to your sGTM server are encrypted so ad blockers can’t block them based on request patterns. Learn more about the enhanced ad blocker protection.

- Same Origin Path - if you use the same-origin approach, enter the path here so both GTM and gtag.js load through it.

- Platform - here you can either:

• Select your CMS platform (such as Shopify, Wordpress, etc.). In this case, you’ll be required to install and configure a Stape app. 

• Select Other to receive a JS snippet in case you’re using another platform or a custom website.

Testing

To verify the setup is working:

1. Open any page on your website.
2. Right-click → Inspect → open the Network tab.
3. Filter requests by your custom subdomain or same-origin path.
4. Look for the GTM request URL - it should return a 200 OK status code.

Use case

A sample scenario is an eCommerce store that sees significant data loss because a large share of its users have ad blockers installed. By enabling Custom Loader, all GTM and GA4 scripts load from a first-party domain, so ad blockers no longer recognize and block them.

You can spot the data loss this way:

1. Compare the order count in your backend against Purchase events in GA4 for the same period. If your backend shows 500 purchases but GA4 only reports 380, the gap could be caused by ad blockers preventing the GTM script from loading in users' browsers entirely. 
2. Enable Custom Loader. This reroutes GTM and GA4 scripts through your first-party domain, so ad blockers can no longer identify and block them by URL pattern.
3. Monitor your GA4 Purchase event count over the same time window and compare it against your backend again.

If the gap persists after enabling Custom Loader, turn on the Enhanced ad blocker protection as well. This encrypts the request URLs so that blocking rules can't match them.