What is ck_subscriber_id?

Who adds it

Kit adds it to links in Broadcast and Sequence emails when the sender switches on the subscriber ID option in advanced tracking.

What it means

A Kit subscriber clicked a link in an email, and the value is their unique subscriber ID. Kit's WordPress plugin and Insights use it to recognise that subscriber on the site.

What to do with it

It identifies a subscriber, so keep it out of shared reports. Kit also offers UTM tags and a hashed email option in the same settings.

How Vireo shows it

Vireo doesn't store click IDs, in the free plugin or in Pro.

In the free plugin, Vireo drops the query string from page addresses, keeping only a few WordPress ones such as p and page_id, so a tagged URL counts as the same page as the untagged one. The visit is counted under the referrer it arrived with.

See Referrers and sources in the docs.

Sources

Automatically append a ?ck_subscriber_id=123 parameter to all the links sent via Broadcast and Sequence emails, where "123" will be replaced with the subscriber's unique ID.

Global advanced tracking - Kit Help Center

Track subscribers who have clicked through your emails to visit your WordPress site

Global advanced tracking - Kit Help Center