Understanding "Referrer" in Marketo: A Throwback to Forms 1.0 and Its Impact Today

There are certain quirks in Marketo’s functionality that can be perplexing, especially for those diving into the technical details. One such quirk is the "referrer" in a Fills Out Form activity, which often causes confusion.

In this blog post, we'll explore the historical context of this behavior, why it happens, and how to interpret the "referrer" in different Marketo activities.

The Legacy of Forms 1.0: Why the "Referrer" Points to the Hosting Page

The reason the "referrer" of a Fills Out Form activity in Marketo points to the page hosting the form instead of the external page (where the user originally came from) lies in the platform's legacy from the early days of Forms 1.0.

Back when Forms 1.0 was commonly used, embedding forms via an IFRAME was the norm. An IFRAME, for those unfamiliar, is a way to embed one HTML document within another. In this setup, the referrer of the IFRAME—essentially the inner document containing the form—is always the hosting document, also known as the outer document. This means that the referrer, in this context, refers to the page where the form is embedded, not where the user came from before reaching this page.

When Marketo transitioned to Forms 2.0, which uses a true same-document <form> element rather than an IFRAME, the system continued to treat the "referrer" of a Fills Out Form activity in the same way as it did during the Forms 1.0 era. Even though the form is no longer embedded within another document, Marketo's tracking still behaves as if it were, leading to some confusion.

While this behavior might seem odd, it's important to recognize that it's not random. It's a byproduct of historical choices made during the development of the platform, which has carried over into the present day. Understanding this can help marketers better interpret their data and avoid misunderstandings when analyzing form submissions.

The Technically Accurate "Referrer": Hidden Fields and Referrer Param

Interestingly, Marketo does use the term "referrer" in a more technically accurate way in other contexts. For example, when you set up a hidden field to be filled from the Referrer Param, it genuinely looks at the previous page that brought the visitor to your site. This is the typical behavior one would expect when dealing with referrer data—the external page that directs the user to your landing page or form.

This distinction is crucial because it highlights the difference between how "referrer" is used in different parts of Marketo. While the Fills Out Form activity might give you the hosting page as the referrer due to legacy reasons, setting up a hidden field to capture the referrer param will provide you with the actual source page, helping you track your leads more accurately.

Visits Web Page Activity: The True HTTP Referrer

Another instance where Marketo aligns with the technically correct use of "referrer" is in the Visits Web Page activity. In this case, the referrer is indeed the actual HTTP referrer, which is captured in the document.referrer. This refers to the URL of the previous web page that the user visited before landing on the current page.

Understanding the nuances of how Marketo handles referrer data in different contexts is key to making sense of your analytics and ensuring you’re interpreting your data correctly.

TL;DR

The concept of "referrer" in Marketo can be confusing due to its historical roots and the different ways it's used across the platform. The key takeaway is that while the "referrer" in a Fills Out Form activity points to the hosting page due to legacy reasons, other features like hidden fields for referrer params and the Visits Web Page activity use the term in a more technically accurate way.