What is utm_source?

Who adds it

Whoever builds the link sets it: a marketer by hand, or a tool that tags links automatically. Email platforms (Kit, beehiiv, Klaviyo), Microsoft Advertising, Buffer and ChatGPT all add their own utm_source value. Google's URL builder docs describe it as the referrer, with examples like google, newsletter4 and billboard.

What it means

It names the site, app or campaign source that sent the visit. Analytics tools read it as the visit's source, even when the browser's referrer says something else or is missing. Google Analytics treats values as case sensitive, so facebook and Facebook end up on separate rows.

What to do with it

Keep values lowercase and consistent, one value per platform, as Google recommends. Since tagged and untagged URLs show the same content, a canonical tag pointing at the clean URL keeps search engines from treating the tagged one as a separate page.

How Vireo shows it

Vireo Pro's UTM campaigns card lists tagged visits by Source, Medium and Campaign, with visitors and pageviews. The tags are read from the first page of each visit, and the same tags feed revenue by source.

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.

When a link carries utm_source with no utm_medium, as ChatGPT's do, Pro's revenue attribution takes the medium from the referrer's source group. With no referrer either, it's labelled campaign.

UTM campaigns are part of Vireo Pro. See UTM campaigns in the docs.

Sources

utm_source : Referrer, for example: google, newsletter4, billboard

URL builders: Collect campaign data with custom URLs - Analytics Help

Parameter values are case sensitive, e.g. utm_source=google is different from utm_source=Google.

URL builders: Collect campaign data with custom URLs - Analytics Help

How to Specify a Canonical with rel="canonical" and Other Methods - Google Search Central