How to use Google Tag Manager to track user ID

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Tracking user IDs in Google Tag Manager (GTM) is crucial for understanding individual user behavior and personalizing user experiences across sessions. The process involves capturing the user ID and passing it into the GTM dataLayer, then using that data to track interactions, link them to user profiles in Google Analytics, or other analytics and marketing tools. Here’s a step-by-step guide to help you track user IDs using Google Tag Manager.

Step 1: Determine Where the User ID Is Stored

The first thing you need to do is figure out where the user ID is available on your site. It could be stored in various places, such as:

  • JavaScript variables: The user ID might be available in a JavaScript variable on the page.
  • Cookies: Sometimes, websites store the user ID in a cookie, which can be accessed by JavaScript.
  • Server-side: The user ID could be passed through the page or via AJAX calls to the front-end, in which case you’d need to capture it from the page source or API response.

If the user ID is already stored as a JavaScript variable or in a cookie, you can directly use it in Google Tag Manager.

Step 2: Capture the User ID in GTM

Once you know where the user ID is located, you can create a variable in GTM to extract it. Depending on where it is stored, you will use different methods to capture the data.

Option 1: Capturing User ID from a JavaScript Variable

If the user ID is stored in a global JavaScript variable (e.g., window.userId), you can capture it using a JavaScript Variable in GTM.

  1. Go to GTM: In your Google Tag Manager account, go to Variables.
  2. Create a New Variable:
    • Click New to create a new variable.
    • Select Variable Type as JavaScript Variable.
    • Enter the name of the JavaScript variable that holds the user ID (e.g., window.userId).
    • Save the variable.

Now GTM will be able to retrieve the user ID whenever the page is loaded, and you can use it for tracking.

Option 2: Capturing User ID from a Cookie

If the user ID is stored in a browser cookie, you can extract it using a First Party Cookie Variable in GTM.

  1. Go to GTM: Navigate to Variables in your GTM container.
  2. Create a New Variable:
    • Click New to create a new variable.
    • Choose Variable Type as First Party Cookie.
    • Enter the name of the cookie where the user ID is stored (e.g., user_id).
    • Save the variable.

GTM will now be able to capture the user ID from the cookie each time the page loads.

Option 3: Capturing User ID from Data Layer

If your website pushes the user ID into the dataLayer, you can easily capture it using a Data Layer Variable.

  1. Go to GTM: Navigate to Variables.
  2. Create a New Variable:
    • Click New to create a new variable.
    • Select Variable Type as Data Layer Variable.
    • In the Data Layer Variable Name field, enter the name of the key where the user ID is stored (e.g., userId).
    • Save the variable.

If the dataLayer.push method is used on your site to send the user ID to the dataLayer, GTM will automatically capture it.

Example of pushing user ID to the dataLayer:

javascript
window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
'event': 'userData',
'userId': '12345'
});

Step 3: Use the User ID in Tags

After capturing the user ID, you can now use it in your tags to send data to tools like Google Analytics, Google Ads, or any other marketing platform.

Example: Sending User ID to Google Analytics

  1. Create a New Tag:
    • In Google Tag Manager, go to Tags.
    • Click New to create a new tag.
    • Choose Tag Type as Google Analytics: Universal Analytics.
  2. Set Track Type to Event:
    • Set the Track Type to Event if you’re tracking specific user actions or Page View if you want to track user data on page load.
    • Under Category, enter a relevant name for the event, like User ID Tracking.
    • Under Action, use the GTM variable that contains the user ID (e.g., {{User ID Variable}}).
    • You can also use this user ID for Label or other parameters.
  3. Add the Google Analytics Settings Variable:
    • Under Google Analytics Settings, select or create your Google Analytics settings variable (which includes your tracking ID).
  4. Set Trigger for the Tag:
    • Add a trigger for this tag. You can choose a Page View trigger to fire the tag on every page load or create a custom trigger for specific events (like button clicks, form submissions, etc.).
  5. Save the Tag.

Step 4: Test the Setup in GTM Preview Mode

Once you’ve configured the variable and tag, use GTM’s Preview Mode to test the tracking:

  1. Click on Preview in GTM and enter your website’s URL.
  2. Once the preview mode is activated, interact with the site and check if the user ID is being pushed to the dataLayer or if the tag is firing correctly.
  3. In the GTM Preview Mode console, you can also inspect the values of variables (e.g., {{User ID Variable}}) to confirm that the user ID is being passed properly.
  4. Verify that the event is showing up in Google Analytics in real-time reports or by checking tag firing in the GTM debugger.

Step 5: Publish Your Changes

Once testing is successful, you can Publish your changes in Google Tag Manager.

Step 6: Compliance and Privacy Considerations

Tracking user IDs requires special attention to privacy regulations like GDPR and CCPA. Be sure that:

  • The user ID doesn’t include personally identifiable information (PII), such as names, email addresses, or phone numbers, unless you have obtained explicit consent.
  • You inform users about the data collection in your privacy policy and provide options to opt-out if necessary.
  • You anonymize data as required to comply with privacy regulations.

Conclusion

Tracking user IDs in Google Tag Manager is an effective way to personalize user experiences, analyze behavior, and create more meaningful data for reporting. By capturing the user ID from JavaScript variables, cookies, or the dataLayer, and pushing it into GTM, you can send this data to platforms like Google Analytics or Google Ads for enhanced tracking and targeting.

Remember to test everything thoroughly in GTM’s preview mode before publishing, and always stay mindful of privacy regulations when tracking user data.

Categories: Digital Marketing