You now want to verify that your Google Tag Manager integration is valid.
To do this, you need to verify your settings using GTM Preview mode.
We will cover the following in this section:
GTM preview mode
Google Tag Manager's preview mode allows you to check which tags are fired and when they are fired.
Feel free to use it after modifying your GTM tags to ensure everything works correctly before publishing and deploying your GTM. Note that preview mode is exclusively in English.
To launch a preview:
Click the Preview button in the top right
In the window that appears, enter the URL of your site.
⚠️ GTM must be integrated into your site for this to work
Following these actions, two windows open:
The first is the Tag Assistant: this is where we will see all events, tags, and other variables evolve as actions are performed in the second window
The second window represents your site: the actions you perform on it will be observable in the Tag Assistant.
💡 Example of a Tag Assistant window:
The summary: it shows you all tags that have been fired or not
An event: by selecting it in the list, it allows you to see if a tag was fired on the correct event or, conversely, why it was not fired
A few examples
Case #1: Facebook Pixel tag fired on the Axeptio event
In this case, we want to verify that our Facebook tag fires correctly on the corresponding Axeptio event: axeptio_activate_facebook_pixel.
By selecting the event in the list of events, we can see that the tag was indeed fired:
By clicking on our "Facebook Pixel" tag, we have the details of its firing, and we can verify why it fired or did not fire:
✅ The observed event is equal to the event required for firing: the tag is therefore fired.
If, as a user, I refused cookies, the Axeptio events do not fire, and therefore the tags attached to them are not fired:
Case #2: Facebook Pixel tag fired by a custom event
In this case, we have added a condition to our "purchase" trigger, which verifies that the Axeptio variable indeed contains "facebook_pixel":
Now let's look at the details:
✅ Our tag was correctly fired on the "purchase" event
✅ It is not the variable name that appears, but its value, so a list of all accepted cookies
✅ Our condition on the Axeptio variable is met: it indeed contains "facebook_pixel"
✅ The observed event is indeed equal to the expected event for firing. Both conditions being met, the tag was correctly fired.
Now, if as a user I refuse cookies:
✅ Since one of the conditions was not met, our tag did not fire.
✅ The observed event is still correct. However, since my variable is empty, it does not contain "facebook_pixel".