AA Cross domain tracking

Hi @karthikh2 

Cross domain tracking from web to web differs from web to app and app to web, so this should probably be taken in stages, tackling web to web fist for the quick win and then app to web and web to app.

For web to web:
The solution depends on if you are using appMeasurment or webSDK and if you are using subdomains or different domains.
I will assume you are using webSDK. 
For subdomains then the ECID should be set against the main domain and you won't need to do anything.
For different domains, you will need to append the visitor ID to the query string.
Here is the link for more information on this and a step by step guide on setting it up.
https://experienceleague.adobe.com/en/docs/experience-platform/web-sdk/commands/appendidentitytourl 

For the app to web:
You will need to work with the app developers to pass the identifiers as query string parameters and attach them to the URL of the webView. This will then automatically get picked up on the web view and set the ECID to the value in the query string. 

For the web to app:
You will need to set up the same link solution as web to web in Launch, then work with the app developers so that they read the ECID parameter from the deep link in the app and update the identity with the new ECID when it's set.

if you use CJA then you can use the Adobe Identity Service to stitch authenticated sessions together to create a person view of the user across the different devices.

Hope this helps.
Dan

Hi,

We manage multiple websites, each tracked through separate Adobe Analytics report suites

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Have you considered tracking all of these into one suite, and using Virtual Report Suites to separate out the individual domains?

While the ECID should be set against your org and therefore maintained (at least per browser / platform)... trying to stitch journeys across different suites is really going to complicate your entire infrastructure... and you can't even get a proper consolidated UV count across these sites....

I have a network of about 30 domains (news sites), each of those domains also has multiple sub-domains (for things like classifieds and obituaries, etc)... ALL of the sites, the apps, the sub-domains, and the "subscription purchase hub" are all tracked into a single suite... I have various virtual suites to make it easier for each business unit to pull their own data, but I can follow a users journey through the entire process.. my marketing channels and tracking codes maintain themselves across the sites and to purchase hub, so I can clearly see what is driving subscriptions....

It really sounds like we have similar flows, so I would highly recommend considering changing up your tracking to make you life easier.... 

Ensure all your websites and apps are using the ECID (formerly MID) to identify users. This ID is key to stitching visits across domains.

Enable Cross-Domain Tracking with appendVisitorIDsTo
Adobe provides the method appendVisitorIDsTo() to append ECID and related IDs to the URL when a user navigates across domains.

Actions:
On every cross-domain link/button (e.g. "Apply" on Website X → Website Y), use Visitor.appendVisitorIDsTo(url) to rewrite the link with ECID.

On the destination page, ensure ECID is extracted from the URL and stored properly via the ECID service.

Use a Shared Data Element to read ECID

Use a rule extension or custom code to rewrite all cross-domain links dynamically

Use a global rule to automatically append ECID to all links pointing to your owned domains