In this blog post, we will look at server-side tag managers (also called "Tag Manager Server Side") and in particular at the Google product available for this purpose. Among other things, we want to explain what it is, what functions a server-side tag manager has, how it works and how it differs from classic tag managers.
In simple terms, a server-side tag manager is used to receive data in a certain form, then manipulate it if necessary and then forward it to a third-party provider.
This sounds trivial at first, but does play a major role. Because normally the tags loaded from your website collect data and would send it directly from the browser to the respective third-party provider. For example, the data collected by Google Analytics would go directly to Google. With server-side tagging, a separate server is used as an intermediate station (also called a proxy), this accepts the collected data, processes it if necessary and then sends it on to the tracking providers.
Despite the similar name, the server-side tag manager cannot really be compared with a client-side tag manager. The latter is only used to play out the tracking scripts ("tags") according to the trigger configuration. Server-side tagging, on the other hand, is about receiving data from users and passing it on to third-party providers.
As with the client-side tag manager, there is also a Google product that we recommend. Essentially, using the server-side GTM (Google Tag Manager) has three major advantages: Firstly, it allows you to use some tracking services, such as Google Analytics, without user consent, as no more personal data is passed on to Google. Secondly, browser tracking preventions can be circumvented. These can restrict or even block tracking in the browser even with full consent. This can have negative effects, such as making it harder to recognise users, or falsely recognising more "new users". Third, it allows Google products, such as a web GTM script or Google Analytics scripts, to be self-hosted, which in turn improves pagespeed scores and Google Core Web Vitals, which in turn improves the user experience on your site.
No, it does not. Both have similar names, but their features are fundamentally different. While the server-side GTM is used to receive data from users, manipulate it if necessary and then forward it to third-party providers, the classic web GTM (or client-side GTM) is used to display tags on the website.
In itself, the server-side Google Tag Manager is a free product for which no licence fees are incurred. Possible costs only arise from the operation of your own server/server network.
The preferred implementation variant is an App Engine service in the Google Cloud. In this way, Google takes care of the provision, maintenance, backup and scaling of the server instances. Alternatively, the tagging server can also be installed in another environment using a provided Docker image.