The effect of webhooks on the channel distribution of your purchase events in GA4

At AdPage, we regularly see that the implementation of E-commerce backend webhooks not only has a significant effect on the number of purchases measured, but also on the channel distribution of your purchase events in Google Analytics 4. Both effects can be experienced as negative and positive. Therefore, in this article, we will explain the most important aspects of this phenomenon and why sending webhooks from the backend of your CMS at the moment of a new order is crucial for the most reliable data possible within your GA4 property.

Backend-webhooks zijn een manier voor een server om automatisch informatie te verzenden naar een andere server of toepassing wanneer er een specifieke gebeurtenis plaatsvindt. Dit laat systemen op de hoogte blijven van veranderingen zonder constant informatie te hoeven opvragen.

Before we delve deeper into the effects, it's worth pausing to consider what backend webhooks actually are. In a previous blog post “Using webhooks for accurate conversion tracking”We have already explained this in detail, but a brief recap is in order. Backend webhooks are HTTP callbacks that enable real-time communication between different web applications. In simple terms: webhooks ensure that systems automatically send messages to other systems when certain events occur. In the case of eCommerce tracking, webhooks are set up on your webshop's backend to immediately send all relevant data to your server container upon a new order. Where regular tracking relies on scripts running in your visitor's browser (client-side), with webhooks, communication takes place directly between the CMS and the AdPage server container (server-side). This makes data collection more reliable as it is no longer dependent on factors such as browser behaviour, cookie blocking, or users abandoning the site early.

The rise in unassigned purchase events

When you implement webhooks, you'll see an increase in purchase events in your GA4 reports, and therefore also an increase in ‘unassigned’ purchase events. This is a logical consequence of the fact that you can now also register purchases from visitors who have refused cookies.

The big advantage of this is that you can display 100% of the number of orders made in GA4, which is enormously valuable for eCommerce dashboarding purposes. This gives you a complete picture of your revenue and the products purchased, something that is not possible with a tracking setup without backend webhooks (except in the backend of your own CMS system).

The downside is that a purchase event without a recognisable client ID, session ID, and session count is considered unassigned by GA4. These events cannot be attributed to a specific channel or campaign. But rest assured: this increase in unassigned events is a positive development, it simply means you are now collecting data that you previously completely missed. If you have no use for these unassigned purchase events from cookie-rejecting visitors, you can simply filter them out in the sGTM container. The GCS parameter is sent along in every webhook so you can filter these webhooks in the sGTM container.

Why you're missing crucial conversion data without webhooks

The impact of webhooks goes far beyond simply registering cookie rejectors. Without backend webhooks, you are guaranteed to miss out on three essential groups of visitors whose purchases can yield valuable attribution data.

The first group consists of early dropouts. These are visitors who, after paying in a payment app, do not return to the thank-you page in the browser. Instead, they close the payment app directly and don't return to the thank-you page in the browser. Their conversion is never recorded in your analytics and marketing platforms, even though they have made a purchase. These missed purchase events can be substantial, especially if you have a lot of mobile shoppers. With webhooks, these purchases are still registered correctly because the conversion data is sent directly from your CMS to GA4, regardless of user behaviour after payment.

The second group is made up of impatient buyers. These are visitors who close the thank you page before it has fully loaded and all tracking scripts have been activated. Their purchase will also remain unregistered for your analytical and marketing platforms if you try to measure the purchase event client-side. With current expectations of fast online experiences, and because you receive a confirmation email with every purchase, it is not unusual for users to not wait for a page to fully load. Webhooks capture this group by sending transaction and user data server-side, regardless of how long or how briefly a user stays on the thank you page.

The third group consists of browser switchers. These are visitors who go through their customer journey in, for example, Google Chrome or the Facebook in-app browser, but after payment via the payment app, they are redirected to the default browser according to the device settings, which is different from the browser they shopped in. Google Analytics will see this as two different sessions since the visitor's client_id, session_id, and session_count will be regenerated, resulting in a complete loss of attribution. Even when you set up webhooks on the thank you page, not from your CMS's backend, you will still not be able to attribute the purchase events of these visitors.

Failing to track these conversions not only leads to an underestimation of your total conversions, but more importantly, to a distorted view of which marketing channels are effective. This can result in incorrect budget decisions and missed growth opportunities. Furthermore, it can lead to frustration within marketing teams if campaigns that are actually performing well are undervalued due to incomplete data.

A more precise channel distribution

One of the most striking effects of a Server-Side Tagging Compared to a setup without backend webhooks, the subdivision of purchase events across different channels by Google Analytics 4 is what we are referring to. Without webhooks, many purchases are incorrectly attributed to Direct traffic. At AdPage, we observe weekly that after implementing our webhooks, the proportion of Direct traffic in purchase events significantly decreases, while the proportion of channels such as Organic Search, Paid Search, Organic Social, and Paid Social increases.

This phenomenon is logically explainable. Without webhooks, attribution data is often lost due to cookie loss, session interruptions, or browser changes. These conversions are then, by default, attributed to direct traffic, leading to an overrepresentation of this channel in your reports. By utilising webhooks, these conversions are correctly attributed to the actual sources that generated the purchase.

For marketing teams, this shift in channel attribution is invaluable. You gain a much more realistic view of which marketing initiatives actually contribute to your revenue. This allows for a more efficient allocation of your marketing budget, enabling you to invest more in channels that deliver proven results but were previously undervalued in your reporting. Furthermore, this more accurate attribution helps in optimising your long-term marketing strategy. You can identify patterns in purchasing behaviour across different channels and tailor your content strategy accordingly to achieve maximum impact at each stage of the customer journey.

Conclusion

The implementation of webhooks is not a luxury but a necessity for any eCommerce entrepreneur or marketer who wants to collect reliable conversion data in GA4. Although you will see an increase in unassigned events, this is far outweighed by the benefits: a complete picture of your revenue and a more accurate breakdown across marketing channels. Curious about how webhooks can improve your GA4 data? Contact AdPage via the button below for a no-obligation consultation.