Cross-Domain Measurement: A Simple Guide to Tracking User Journeys Across Multiple Domains

August 27, 2024 |

Written by Amber

Hey there! Ever wondered how to keep track of users as they hop from one of your websites to another? It can feel like trying to follow a trail of breadcrumbs, right? Well, that’s where cross-domain measurement comes into play. Also known as “site linking,” cross-domain measurement helps unify user sessions across different domains, giving you accurate data and better insights.

I’m Amber, the Analytics Guru, and I’ve been diving into the world of conversion tracking for over 7 years. My experience spans across platforms like Google Ads, Meta Ads, Microsoft Bing, and Shopify e-commerce. I’m passionate about making sure our campaigns run smoothly and deliver outstanding results.

Conversion tracking is crucial to our daily operations at Utopiads, and cross-domain measurement is a key part of that. Whether you’re managing multiple websites or simply looking to get a clearer picture of your user’s journey, setting up cross-domain tracking can be a game-changer.

In this post, I’ll walk you through the basics of cross-domain measurement, so you can start tracking those user journeys like a pro. Ready to dive in?

What is Cross-Domain Tracking?

Imagine a customer starts on your main site and then moves to a separate domain for your shopping cart. Without cross-domain tracking, Google Ads might misattribute the source of the traffic, leading to inaccurate data. By setting up cross-domain tracking, you ensure that a user’s journey is tracked as one continuous session, even if it spans multiple domains.

Do You Need Cross-Domain Tracking?

Here’s a simple flowchart to help you decide whether you need to install it. In summary, do you have separate domains for different parts of your business? For example, mainwebsite.com and shoppingcart.com. If you answered yes, you need cross-domain tracking.

Benefits of Cross-Domain Tracking

Accurate User Tracking: Get a clearer view of your traffic, engagement, and overall web performance.
Better Attribution: Correctly attribute conversions to their sources, especially useful for reporting on paid media investments like Google Ads.
Consistent Data: Maintain reliable and consistent data across multiple domains.

Determining How Many GTM Containers to Use

One of the most common questions that arise when using GTM to track multiple domains is: How many containers do you need? The number of containers required will ultimately depend on the specific use case.

Some situations that might call for dedicated containers for each website include:

Tracking websites that are completely different in terms of content and functionality (e.g., an online store, a blog, and a support page).
Running a wide range of paid media campaigns that need to be tracked across multiple websites.
Brands that have multiple agencies running campaigns across their websites require different tracking tags and possibly different access needs.

If you’re looking to track websites that are very similar or related, I recommend using the same container for all of them. Most likely, you’ll be tracking related activities across these websites, and it can also make things easier to maintain when applying changes.

Setting Up Cross-Domain Tracking with Google Tag Manager and Google Ads

Prerequisites

To set up conversion tracking on your website, you need to ensure you have access to the following:

A Google Ads account
A Google Tag Manager (GTM) account

(*For this blog post, we are going to assume you have already installed GTM on your website.)

Ready to dive in? Follow these steps to set up cross-domain tracking:

Google Tag Manager Configuration:

1. Log in to your Google Tag Manager (GTM) account.

2. Choose the container that corresponds to your website.

3. Click “New” and select the “Conversion Linker tag.”

4. Ensure that “Enable Linking on All Page URLs” and “Enable linking across domains” are checked.

5. Under “Auto Link Domains,” enter your domains separated by commas (e.g., example1.com, example2.com).

6. Set the URL position to “Query parameter.”

7. Check “Accept incoming linker parameters.”

Test and Verify Your Setup:

Click on the “Preview” button in the top right corner of Google Tag Manager.
Open your website in a new tab with the preview mode enabled.
Perform a test journey across the domains you set up.

Ensure that the Google Ads ID (‘AW – XXXXXXXXXXX’) remains the same as you navigate between domains.

Publish Your Changes:

After verifying that everything is working correctly in preview mode, go back to Google Tag Manager.
Click on “Submit” in the top right corner.
Add a version name and description (e.g., “Cross-Domain Tracking Setup”).
Click “Publish” to make your changes live.

Wrapping Up

If your online business uses multiple domains but just one Google Ads ID, cross-domain tracking is a must-have. It helps keep your data honest and gives you a clearer picture of user engagement. Whether you’re using Google Ads or GA4, setting up cross-domain tracking properly will ensure accurate attribution and a better understanding of your user behavior.

So, go ahead and get started with cross-domain tracking. Make your data work for you! Happy tracking!

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