Preview and debug containers

Make sure your tag configurations function as expected.

Google Tag Manager’s Preview Mode allows you to browse a site on which your container code is implemented as if the current container draft was deployed, so that you can test a container configuration before it is published. Sites with Preview Mode enabled will display a debug window so that you can inspect which tags fired and in which order.

Enable Preview Mode

To enable Preview Mode for the current workspace, click Preview. Tag manager will show a banner across the top of the workspace overview page to indicate that Preview Mode is active.

You can also preview any older version of a container. To preview a previous version of your container:

  1. In the left navigation, click Versions.
  2. Find the version you would like to work with and select Action and then Preview.

Use Preview Mode

Once Preview Mode is enabled, navigate to the site where the container is implemented and you will see the debug console open in a separate browser tab or window. The debug console shows detailed information about your tags, including how tags fired and what data is being processed. The console window will appear only on the same browser that was used to enable Preview Mode, or for shared users, and is not visible to your regular website visitors.

Use the information in the debug console to find out if tags and triggers fire properly and what data they pass to their respective services. As you click through your previewed website, the debug console will update information about how your tags are fired. You can use this information to see if a tag fired successfully, and what triggered (or did not trigger) its firing status.

The top navigation bar lists options to access information about Tags, Variables, and the Data Layer, and the left navigation bar shows a list of events.

  • Tags: Click Tags to see which tags fired and which tags did not fire. Click a tag to view the tag's properties and associated triggers. When an event is selected in the left column, the Tags tab will show the status of tags for that event.
  • Variables: The Variables tab will display detailed information about variables in the selected event, including the type of variable, the type of data returned, and the resolved value. Select an event in the left navigation to view the status of variables at the time the event fired.

  • Data Layer: The Data Layer tab will show the exact message as it was pushed to the data layer for the selected event, and what the data layer looks like after the message transaction is complete. Select an event in the left navigation to view the status of the data layer at the time the event fired.
The debug window is not currently available for mobile app containers. To learn more about how to preview and debug mobile app containers, read the iOS and Android developer documentation.

Share Preview Mode

When Preview Mode is enabled, the previewed container configuration and debug pane are only visible from the same browser from where you activated Preview Mode. You can share this preview with others with a custom generated URL.

To share a preview of your workspace configuration with a colleague:

  1. Click Share Preview from the preview notification banner.
  2. In the Share Preview dialog, enter your target website domain (e.g.
  3. Copy the resulting preview URL from the indicated box.
  4. Paste the copied preview URL into an electronic message and send it to a colleague. The preview URL will take the user to a landing page where they will be informed that their browser has been enabled for Preview Mode.

Exit Preview Mode

To exit Preview Mode from your container:

  1. Click Workspace.
  2. Click Leave Preview Mode.

To exit a shared Preview Mode:

  1. Click the link received to go to the shared preview landing page.
  2. Click Exit preview and debug mode.
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