March 22 2021

Tracking the Visitor Journey Across Multiple Domains

Understanding the visitor journey is one of the best ways to maximize your digital marketing strategy. The more you can know about where your visitors are coming from, how they are interacting with your website and how they are converting will let you allocate your time and marketing dollars more effectively. One roadblock to fully understanding the visitor journey is when it spans multiple websites or platforms. Often the conversion itself (e.g. contact form, application form) happens on another domain, making it seemingly impossible or at least difficult to connect the dots through out-of-the-box analytics tracking.
Luckily there are steps you can take to connect the steps along your visitor’s journey from awareness to conversion. For websites using Google Analytics and Google Tag Manager (GTM) to record visitor traffic it’s a matter of making sure your inbound traffic is accurately tagged and that your third-party partners are included in your cross-domain tracking strategy. The result? You might just be able to track ROI from your marketing efforts – the golden ticket all marketers desire.
Note that the steps to get here will require you to work with a certified Google Analytics expert or agency, since this can get rather complicated quickly.

How Cross-Domain Tracking Works and How to Enable It

Cross-domain tracking is the method of recording hits on multiple domains under one session in Google Analytics. If a visitor arrives on your website from a paid marketing campaign for example, and then clicks to another domain being tracked and completes a conversion, you can tie that conversion back to the marketing campaign that initially brought them to your website. If you’re tracking multiple domains in Google Analytics and you don’t have cross-domain tracking enabled, the session data will not carry over from one domain to the other. While Analytics will still be tracked on the third-party domain, it will show as a separate session from the visit to your domain, which makes it impossible to connect the two.
Setting up cross-domain tracking is something that can be very simple in some cases, and very difficult in others. It all depends on the third-party you’re linking to. At the most basic level, the steps to enabling cross-domain tracking are:

  • Enabling the cross-domain linking setting

  • Defining which domains you want to link

  • Setting those domains as “referral exclusions”

  • Adding your tracking code on all linked domains

google tag manager settingsGoogle Analytics referral exclusion list
Third Party Tracking through Google Tag Manager and Manual Placement in Google Analytics

The process is slightly different if you’re using Google Tag Manager or a manually placed Analytics snippet in your website’s code (javascript or gTag implementation). Google Tag Manager has a field where you can set the field “allowLinker” to “true”. If you have manually placed Google Analytics code on your website you’ll need to update it to add an {allowLinker: true} statement.
Google Tag Manager also has a field where you can define a comma-separated list of the domains you want to link (,, The manual implementation in your website code requires this same list entered as ga('linker:autoLink', ['', '']);. Once you’ve defined your domains, Google will append a linking query string to clicks that happen from one of these domains to the other. This tells Google that when the page is loaded on the third-party domain it should be associated with the session tied to that query string. It’s important to remember to include the full domain you’re linking, as Google may consider some URLs not in your tracking plan to be subdomains of those you are. An example would be if you’re including your own website - -  in the cross-domain tracking plan, but you have a vendor using as their domain which is not in your tracking plan. Analytics will try to link to the domain if you just use as the domain in your list. The way around this is to have be the domain you include in your list of linked domains and as your referral exclusion.
The last step is done in your Google Analytics Admin Settings, under the Property column nested within the Tracking Info settings. There is an area called Referral Exclusion List which tells your Google Analytics which domains should not be counted as Referrals in your Acquisition reports. The same domains defined in your tracking plan should be added one by one as exclusions. If this step is missed your third-party traffic could look like it was referred from your website, instead of a continuation of that visit.
One of the most important steps in all of this is making sure that the third-party domains have the tracking code placed. This means that your Google Tag Manager container code, or your Google Analytics snippet should be added on all pages a user could visit on these domains. If you’re using Google Tag Manager this can be done as the first step in the process, as you can make changes to your tags and settings in GTM after the code is placed. If you’re using Google Analytics (Universal or gTag javascript) you should add the linking parameters before you provide the code to any third-party websites. Before starting any of this effort, consult with your third-party vendors to know what they can accommodate, and what initial and ongoing costs may be on their end to implement.

Universal analytics linker
Global site tag linkerTesting Your Cross-Domain Tracking

If you’ve taken the steps outlined above, a user should be able to arrive on your website and navigate to a tracked third-party website all within the same Session. However, there are some issues which can cause your tracking not to work. Before you just assume that your cross-domain tracking is working you should test the process yourself. The easiest way to test whether your tracking works is by using Google Analytics’ Realtime Reporting. These reports show you your website traffic in real time (hence the name) and can help you debug any issues you may be having.
What’s very helpful about these Realtime reports is that you can select a traffic source and then view all Realtime reporting only for that traffic source. Since Google’s own Campaign URL Builder tool lets you create UTM tracking links, you can create a unique tagged URL which will let you define your traffic source and see whether it carries from one domain to another. You’ll want to create a testing UTM link for your own website such as:
When you access your website using your testing link you should see the source/medium of Test/Test appear in your Realtime reporting under Traffic Sources. On your website if you click to one of your tracked third-party domains you will hopefully see two things. The first is that the linking query string gets appended to the URL you clicked, and the second is that you should see the third-party page you landed on in your Realtime content report attributed to your Test traffic source. As you navigate through to additional pages on the third-party domain, those pages should also show as being tied to your Test source.
You can double check that cross-domain tracking is working by checking the source/medium of traffic to the third-party pages in the Behavior > Site Content > All Pages report in Google Analytics. You can search for the third-party page and then add a Secondary Dimension of source/medium to see which traffic sources are reflected on that page. If done correctly you should see your Test traffic reflected, as well as regular visitor traffic from channels like organic and paid search and social media. 

Tracking Conversions on Third Party Websites

Getting your third-party traffic linked in Google Analytics is the first step into a larger world of tracking the visitor journey. Depending on the platform, you’ll be able to see many actions that were previously unknown. This could be interactions with articles or videos on an educational resource website, or various steps of a form in an ecommerce or application website. By default, Google Analytics fires a Pageview when a new page loads in the browser, so the actions you see will initially be limited to which pages load on the third-party website. Some third-parties have URLs that are very indicative of what the user is seeing, while some URLs are a string of numbers and letters that don’t mean much when laid out in a report. Furthermore, some websites change the content a visitor is seeing on a page without actually loading a new page, so Google Analytics doesn’t fire another Pageview.
Google Analytics allows you to define conversions (Goals) when a visitor gets to a specific Destination URL, or when they trigger a specific event. Depending on what you’re able to track on the third-party site you might be able to easily identify the final URL that indicates a conversion has occurred and set it as a Goal. If there isn’t a unique URL that indicates a conversion, you could use GTM to tag a click that signifies an important action has been performed. Some vendors will even provide documentation about the URLs seen on their platforms to help you better understand where your conversions can be placed. If there are multiple URL steps in the process, Google Analytics lets you create a Funnel Goal, which when created correctly will show you how visitors continue or drop out at different points of the conversion process.

Google Analytics goal setup
Identifying these conversion points and tracking them via Google Tag Manager will give you a better understanding of how your visitors are completing, or abandoning, the key actions you’re driving towards. If your cross-domain tracking is implemented correctly, you’ll be able to accurately tie back these third-party conversions to your various marketing campaigns. If you’re going the URL route and the vendor hasn’t specifically told you which URL corresponds with a conversion, you can look in your reporting for anything that looks like /confirmation or /submitted, or you can walk through the process yourself to see what URLs appear at different steps of the process. Many vendors also offer a test version of their application where you can verify everything is working without submitting a live conversion. This method is also helpful if you’re manually adding conversion tags based on a click, as this might require several rounds of testing in GTM.
Google Analytics goal tracking

Visualizing Your Conversions in Google Data Studio

If you want to get as much detail as possible about your third-party conversions, Google Data Studio allows you to visualize metrics in a variety of ways. You can create heatmapped charts showing conversions by city, tables with up to ten columns of visitor breakdown per conversion, and even pull in audience segments to see what other actions your audience performs prior to conversion. This can be extremely helpful if you need to present your data to a team who wants a high-level analysis of campaign successes, and help you make better choices for budget allocation based on which marketing tactics are driving the most conversions.

How to Talk to your Third Parties about Adding Code

The first step to linking your domain with third-parties to track more of the visitor journey is to get the vendor to add your tracking code. Many third-party platforms have different processes for adding codes, while some simply don’t allow it at all. When you do ask a third-party if they allow for Google Tag Manager or Google Analytics code to be placed, ZAG has found that asking the following questions can be very helpful:

  • Does your platform charge any one-time or recurring fees to host tracking codes?

  • Does your platform provide any documentation on the data that can be captured by analytics tracking?

  • Is there any variable data related to conversions that can be captured via Google Tag Manager?

    • Note: Google Analytics does not allow for personally-identifying-information to be captured in their reporting platform

  • Is there a test version of the platform where the analytics tracking can be confirmed prior to being pushed to the live site?

While all of this might seem like very advanced analytics, the simplified version is that in order to track the full visitor journey sometimes you need to go beyond what you’re already tracking. If that includes a visit to a third-party, you just need to update where and how your analytics tracks. This will help you better explain the performance of your marketing campaigns and allocate budget and time towards strategies proven to increase conversions.

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posted by
Patrick Trayes
Patrick Trayes
Associate Director of Client Analytics

ZAG Interactive is a full-service digital agency in Glastonbury, CT, offering website design, development, marketing and digital strategy to clients nationwide. See current job openings.
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