FreePower-ups

sGTM Preview Header config

sGTM Preview Header config lets you see all incoming server-side requests in the sGTM debugger, not just those from the web container. Review and debug requests from CRMs, backend systems, mobile apps, APIs, and webhooks to check how your server GTM setup processes the data and whether the expected tags fire.

How to access sGTM Preview Header config

sGTM Preview Header config is available on Stape Free plans and higher. You can find it in the Power-ups tab in your Stape account.

Open your Stape account → Choose your recent sGTM container → Click Power-ups → Find sGTM Preview Header config and click Use.

sGTM Preview Header config

How sGTM Preview Header config works

sGTM Preview Header config stores your current X-Gtm-Server-Preview value in Stape for a test session. Stape uses this value to send incoming test requests to your open sGTM preview session, so they appear in the debugger.

You can also limit testing by webhook path or IP address. This lets you send selected test requests to preview while regular traffic continues to your sGTM container as usual.

Benefits of sGTM Preview Header config

  • Preview requests without editing their headers. Add the preview token in Stape instead of configuring the X-Gtm-Server-Preview header in each backend system, app, API, or webhook tool. This also helps when an external tool does not let you add custom HTTP headers.
  • Test selected requests without interrupting production traffic. Use an IP address, a URL path, or both to send matching requests to preview while other traffic continues to your server GTM container as normal.
  • Check requests from other browser sessions. See requests triggered in a different browser or an incognito tab inside the same server GTM debugger.
  • Find the source of missing or incorrect data. Inspect the incoming payload, client claim, event data, variables, and fired tags to understand whether the issue starts in the data source or inside your server GTM setup.

Debug requests from external data sources

sGTM Preview Header config shows requests from CRMs, order systems, payment tools, and apps in the sGTM debugger. Inspect the incoming data and fix setup issues before publishing your changes.

Related to this solution

Debug incoming webhooks in Google Tag Manager server preview
Apr 16, 2025

Blog

Debug incoming webhooks in Google Tag Manager server preview

One of the ways to use server-side tracking is sending data directly from your server endpoint to the server GTM container. This guide will show how you can send requests to the GTM server container with webhooks and how to see and test webhook data in the server Google Tag Manager container. We’ll also go over some common scenarios where it makes sense technically and practically speaking.

Send data from CRM to Facebook Conversions API using webhooks
Sep 11, 2026

Blog

Send data from CRM to Facebook Conversions API using webhooks

Track offline conversions by sending CRM data to Facebook Conversions API via webhooks. Easily set up with GTM server containers for accurate attribution. The most popular way of integrating Facebook Conversions API is using the Google Tag Manager server container. But there are other ways to do that: using Zapier, direct integration, integration with the CRM using webhooks, and much more.

Guide to debugging and monitoring server-side tracking configuration
Aug 21, 2026

Blog

Guide to debugging and monitoring server-side tracking configuration

Learn how to debug server-side tracking with Stape’s tools, including sGTM Debugger, logs, and monitoring, to ensure accurate and efficient data tracking.

We have more than 200 000 happy clients

Try Stape for all things server-side