Google Tag Assistant Guide | BCS Google Tag Assistant Guide | BCSBCS

Google Tag Assistant Guide

Google Tag Manager BCS 4 years ago (2020-10-19) 5993 Views 0 Comments

The debugging of Google Tag Manager was changed to Tag Assistant on October 16, 2020. This is the only test method. Previously, it was Preview Model, or click Preview in the upper right corner, but the test method has been different. New debugging The method Tag Assistant is to support Google Analytics V4.

What is Tag Assistant

Tag Assistant was originally a Chrome plug-in for Google Analytics debugging, which can be downloaded in the Chrome application market, and is now integrated into Google Tag Manager to support the debugging of Google Analytics V4.

Preview Model VS  Tag Assistant

Debugging results: Preview Model displays the debugging results directly at the bottom of the test page through the iframe, and Tag Assistant records the debugging results on a separate page.

Control of test status: Preview Model is a third-party cookie, a cookie at, and Tag Assistant is a first-party cozokie/LocalStorage, and a file named __TAG_ASSISTANT is generated during debugging. First-party cookie.

Information displayed: Tag Assistant displays DataLayer, Tag Assistant displays DataLayer and API Call information


Advantages of Tag Assistant

  • Support the debugging of Google Analytics V4: The appearance of the Tag Assistant is mainly to support the testing of Google Analytics V4.
  • Can record the test results of multiple pages or behaviors: Tag Assistant records the test results on a single page. As long as you do not close this page, the test results will always be retained.
  • Debugging without authorization by Google Tag Manager: Preview Model can be debugged only after authorization, while Tag Assistant can share test connections to enable third-party testing without authorization.
  • Show more information: such as API Call
  • Support the debugging of server-side deployment, GTM supports server-side deployment, but also requires testing, and Tag Assistant is required.

How To Use Tag Assistant For Debugging

This part mainly talks about the debugging and use of Tag Assistant.

Two Ways To Open Tag Assistant

There are two entrances to open debugging:

  • One is to click Preview in the upper right corner
  • One is to click Preview under  version


Google Tag Assistant Guide

After clicking Preview, a new page will open at, this page is used to set up the test page:

Google Tag Assistant Guide


Fill in the URL to be tested and click Start to start:

Google Tag Assistant Guide


Tag Assistant will connect to the page to be tested and open it. The opened test page will have a field of gtm_debug=x. If the url we want to test is, the url it opens is, and there is a small Debugger connected window in the lower right corner, which means it is in the test state.

Google Tag Assistant Guide


The interface of Tag Assistant is as follows:

Google Tag Assistant Guide


Connected in the upper left corner indicates the test status.

GTM-PHXQ69M, which means the container currently being tested, it can be a GTM container or a measurement ID

Summary: indicates that the behavior is monitored

output of GTM-: Indicates the specific Tag, data transfer or error triggered.



If you open the debugging state, there will be two pages, one is Tag Assistant, which records the results of debugging data, and the other is the page you want to debug. There will be a field of gtm_debug=x on the URL, and there will be a small Debugger connected window in the lower right corner. .

This means that it enters the debugging state.

All your data on the debugging page is recorded by the Tag Assistant page, so you only need to simulate the action that needs to be operated, and then check whether the corresponding Tag is triggered in the Tag Assistant.

As mentioned earlier, Tag Assistant is to support Google Analytics V4, that is, Tag Assistant can be used for GTM debugging or Google Analytics V4 debugging. The content displayed on the two pages is slightly different.

Whether you are testing GTM or Google Analytics V4 depends on your choice of container or measurement ID in the upper right corner:

Google Tag Assistant Guide

If you choose the beginning of GTM, it is the GTM container and GTM debugging is performed.

If you choose the beginning of G, it is the measurement ID, and the debugging of Google Analytics V4 is performed.

GTM Debugging

After selecting the GTM container ID, the test interface of Tag Assistant is as follows:

Google Tag Assistant Guide

There is a downward black triangle/arrow on the left to indicate the PV, the red box indicates the behavior in this PV, and there is a yellow circle next to it, which indicates the status of the mark.

  • A grey icon with an ‘x’ indicates that no code was found on the page
  • A green indicator will show if a valid tag was found. The number in the icon indicates the number of tags that were found
  • A blue indicator will show there are suggestions on improving overall tagging health
  • A yellow indicator will show that a tag was found with minor implementation issues
  • A red indicator will show that a tag was found with critical implementation issues

The following numbers with numbers indicate the behavior on this page, such as Container Loaded, DOM Ready, Window Loaded, Click, etc.

The Output Of GTM on the right-identifies the triggered Tags.

The test idea here is the same as the original Preview Model: select the corresponding behavior on the left side, you can see which Tag triggers on the right side, you can also see whether the value in the variable is obtained correctly, or see what is sent by the data layer Message, or see what is wrong in Error.


Google Analytics V4 Debugging

If your website is deployed with Google Analytics V4 code, you can select the container ID/measurement ID in the upper left corner. The test interface of Tag Assistant is as follows:

Google Tag Assistant Guide

The Google Analytics V4 test interface is basically the same as GTM, mainly the output of G-here is a little different, here use hit sent instead of Tag and Variable. Clicking on it, in fact, clicking on the Tag, you can see what data the corresponding Tag sends:


Google Tag Assistant Guide

See if the above settings are the same as those set by your own tracking.

The new test result interface also has some differences. For example, I choose Container Loaded:

Google Tag Assistant Guide

Here will also prompt the API used for this behavior. This is very useful when debugging Google Analytics V4. You can see the triggering of specific events in Google Analytics V4.

Google Tag Assistant Guide

Share Preview

Share Preview is a way that requires external experts to test, but does not want to authorize it.

Click Share Preview under version management to share the test:

Google Tag Assistant Guide

A setting interface for sharing the test will pop up:

Google Tag Assistant Guide

Destination URL: is the page to be tested

The link below is the link to be shared.

Stop Preview

To turn off debugging, click the cross in the upper right corner of the Tag Assistant page:

Google Tag Assistant Guide


Since Tag Assistant connects to open the test URL during debugging, it can be understood as jumping to the test page through Tag Assistant, so the test traffic will identify the referral from For the data to be accurate, please refer to the referral exclusion The list excludes it.

If you don't understand, You can leave a comment below.
Like (1)
Post my comment
Cancel comment
Expression Bold Strikethrough Center Italic

Hi, you need to fill in your nickname and email!

  • Nickname (required)
  • Email (required)
  • Website