The most frustrating, but useful way to track your traffic across platforms.
Step 1: Prepare Your Domains
Identify Domains: List all the domains that will share data (e.g., domainA.com and domainB.com).
Ensure Both Sites Have GTM Installed: Make sure Google Tag Manager is installed on both domains.
Step 2: Configure GTM Settings
Open GTM: Log in to your GTM account.
Select Your Container: Choose the container associated with your primary domain (the one from which users will be redirected).
Step 3: Enable Cross-Domain Tracking
Go to Admin: Click on the "Admin" tab in the left sidebar.
Select Container Settings: Under the container you’re working with, select "Container Settings."
Cross-Domain Tracking: Find the option for "Cross-Domain Tracking" and enter the list of domains separated by commas (e.g., domainA.com,domainB.com).
Save Changes.
Step 4: Modify Your Google Analytics Tag
Go to Tags: In the GTM workspace, select "Tags."
Edit Your Google Analytics Tag: Find and click on the tag that sends data to Google Analytics (GA).
Enable Linker: Under the "More Settings" section, expand "Fields to Set" and add a new field:
Field Name: allowLinker
Value: true
Add Auto Link Domains: Under "Cross Domain Tracking," set:
Auto Link Domains: Add your domains (e.g., domainA.com,domainB.com).
Step 5: Set Up URL Parameters
Linking the Domains: Ensure that all links between the two domains are modified to include the linker parameter:
Use the GTM built-in {{Click URL}} variable when creating links.
Example: When linking to domainB.com, use:javascriptCopy code<a href="https://domainB.com?utm_source=domainA&utm_medium=referral" target="_blank">Go to Domain B</a>
Step 6: Test Your Implementation
Preview Mode: Enable preview mode in GTM to test your changes.
Check Linker Parameter: Navigate between your domains and check the URL for the presence of ?_ga=... or similar linker parameters.
Google Analytics Debugger: Use the Google Analytics Debugger extension in Chrome to confirm that the data is being sent correctly to GA.
Step 7: Publish Changes
Publish Your Container: Once everything is confirmed working, go back to GTM and publish your changes.
Step 8: Verify Data in Google Analytics
Check Real-Time Reports: Go to Google Analytics and navigate to the Real-Time section to verify that sessions are being tracked across both domains.
Review Behavior Reports: After a few days, check behavior reports to ensure users are navigating between domains correctly.
Additional Considerations
Same GA Property: Ensure both domains are using the same Google Analytics property for cross-domain tracking to work effectively.
Cookie Settings: Make sure both domains use the same cookie settings (e.g., same cookie domain).
Here are some complex scenarios that can arise with cross-domain tracking, along with considerations for each:
1. Subdomains and Root Domains
Situation: You have a main website (e.g., example.com) and multiple subdomains (e.g., shop.example.com, blog.example.com).
Consideration: Ensure that cross-domain tracking settings include both the root domain and all subdomains. Configure the GA property to recognize subdomains as part of the same site for consistent tracking.
2. Multiple Google Analytics Properties
Situation: You are tracking different domains with separate GA properties but want to analyze user behavior across them.
Consideration: Implement user ID tracking in GA and ensure that users are logged in across domains. Set up a consolidated reporting view or use a tool like Google Data Studio to combine data from different properties.
3. E-commerce Transactions Across Domains
Situation: Users complete transactions on one domain (e.g., shop.example.com) but are redirected to a confirmation page on another domain (e.g., example.com).
Consideration: Pass transaction details as URL parameters to the confirmation page. Implement cross-domain tracking to ensure that the entire transaction is tracked in GA, including revenue attribution.
4. Cookie SameSite Restrictions
Situation: New browser privacy features restrict third-party cookies, impacting cross-domain tracking.
Consideration: Use first-party cookies and set the SameSite attribute appropriately to allow cross-domain tracking. Review your cookie settings to ensure compatibility with browser updates.
5. SPA (Single Page Application) Navigation
Situation: Your site uses a single-page application (SPA) framework (like React or Angular) that loads content dynamically without page reloads.
Consideration: Implement virtual pageviews in GTM to track navigation events. Use custom events to signal GA when users navigate within the SPA, ensuring accurate tracking of user interactions.
6. Tracking User Behavior on External Links
Situation: You link to external sites and want to track how users interact with those links.
Consideration: Use outbound link tracking in GTM to monitor clicks. Set up event tracking to capture user engagement with external links, ensuring these interactions are logged in GA.
7. Multi-Channel Funnels
Situation: Users interact with multiple channels before converting, spanning across different domains.
Consideration: Implement a comprehensive UTM parameter strategy to track the entire user journey across different channels. Analyze the multi-channel funnel reports in GA to understand the impact of each touchpoint.
8. Cross-Domain Tracking in Mobile Apps
Situation: Your web platform links to a mobile app for certain functionalities (e.g., checkout).
Consideration: Use deep linking techniques to ensure users transitioning between the web and mobile app maintain tracking. Implement Firebase Analytics alongside GA for comprehensive mobile tracking.
9. GDPR and Privacy Compliance
Situation: Users from the EU access your sites, requiring compliance with GDPR regulations.
Consideration: Ensure that you have a clear consent mechanism for tracking. Use a consent management platform to obtain user consent before enabling cross-domain tracking.
10. Custom Domains for Landing Pages
Situation: You have separate landing pages hosted on different domains for marketing campaigns.
Consideration: Set up cross-domain tracking in GTM for all landing pages and ensure that UTM parameters are correctly configured to track campaign performance across different domains.
Cross-domain tracking can feel like navigating a maze, especially with multiple platforms and websites in play. But while it’s tricky, mastering it is key to getting a clear, unified view of your users' journey across domains. With the right tools, such as Google Tag Manager and proper UTM parameters, you can track users as they hop between your different properties, giving you valuable insights into behavior and performance.
Remember, it's okay if it feels a bit overwhelming at first. By following the steps carefully, testing, and making sure everything is set up correctly, you’ll soon have seamless cross-domain tracking that lets you see the full picture of your digital presence. And if it all feels too complicated—don’t worry, that’s what guides (and Google’s support team) are for!