UTM Tracking - what's the best method?

[Nina_Valtcheva5]

I've been looking around at various threads on the community and seems there are 2 main ways people are building Marketo programs for digital UTM tracking - either using "Fills Out Form" with a "Referrer" constraint OR using UTM values as fields. For example, if you want to track Paid Social through LinkedIn. We are currently using the latter - so we have the standard UTM hidden fields on our forms and we're using them as filter constraints like this:

Wondering if that's the best method, or if using Fills Out Form with a Referrer constraint is better, so something like this instead where the UTM query string is specified in the Referrer.

Pros/Cons to each method?

[SanfordWhiteman · Accepted solution]

The Referrer constraint isn't useful if you already have hidden fields dedicated to capturing each interesting URL parameter, and if the page hosting the form is not relevant to you.

Referrer can help you reproduce URL params that you forgot to capture into fields (as part of a Smart List filter, not a Smart Campaign trigger in that case). It can help you conserve Marketo fields, if you're deeply concerned about the number of fields (I would not be -- UTM tracking fields are essential). And it lets you match the page's hostname, pathname, and hash, unlike out-of-the-box hidden fields that use the querystring only.

An inherent bug with string [contains] matching, not just in Marketo but in any platform/language, is that it's not actually parsing the URL into its constituent parts. This can lead to false positives. For example, the strings "?key1=value" and "?key1=value2" both match the string [contains] "key1=value" (because the strings are not mutually exclusive for their full length).  When you use hidden fields, the URL is first parsed properly using JS, so this kind of thing cannot happen.

[Nina_Valtcheva5]

Thanks Sanford! Yeah I was never sure why referrer would be used instead of the actual UTM values so your points are really helpful.