We’re currently testing a setup where we track multiple websites (e.g., xyz.net, abcd.net, and abcde.ca) using a single Piwik PRO container.
Here’s our exact setup:
We’ve added all domains under one site/app address in the Piwik PRO settings.
We are using the same tracking code (tag manager container) on each domain.
We did not configure cross-domain linking manually (e.g., no URL parameter passing or visitor ID override).
Users are visiting these sites directly, not through links between the domains.
What we’re observing:
The same Visitor ID is being generated across all domains — even when accessed independently. This suggests that Piwik PRO is somehow maintaining user identification across domains with this configuration.
Our main question:
Is this behavior expected and supported by Piwik PRO as a valid method for identifying users across multiple domains — even without referral links or manual ID sync?
We’re especially interested in:
Whether this is reliable long-term, or if we’re just seeing temporary behavior due to shared cookies or caching.
Whether browser privacy features (e.g., Safari ITP, Firefox ETP, Chrome’s partitioned cookies) will block or eventually interfere with this method.
Any official guidance or best practices from Piwik PRO for multi-domain user identification without requiring referral linking.
If anyone has experience with this setup or feedback from Piwik PRO support/docs, we’d love to hear it!
It’s possible that you have session hash turned on and based on your parameters Piwik PRO detected that you are same visitor. If you visited website A and visit website B while all parameters used by session hash are the same and there’s no bigger difference between two events than 30 minutes your session will be continued meaning you’re be the same visitor, but only from the perspective of that session as session hash only works for session recognition and not returning visitor recognition
You mentioned that there are no links between domains, but you still want to identify same users. For that I suggest setting up userID if it’s possible to get unique identifier:
Here is article that explains different scenarios for counting sessions:
To answer your questions directly: - is it reliable long term? it depends on your setup and tech stack your users are using. It’s as reliable as session hash mechanism. There are rare situations where many users visit someone website from one IP with same system, and same computer setup - in that case they might be detected at one user - browser privacy features - yes they might interfere with visitor ID based on cookie, but most of them shouldn’t interfere with session hash
@Tuhin Methods above use internal mechanisms to detect it’s same user in one session. UserID would be better solution in your case if it’s possible to assign some unique identifier for each user.
What we’re observing:
Our main question: