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Benefits of Server Side Tagging (with Google Tag Manager)

You have probably heard multiple people talking about how server-side tagging is the future of analytics implementations. But before you dedicate time and resources to this topic, you want to better understand the potential benefits of this solution.

Well, look no further. In this blog post, I will explain the benefits of server side tagging (with Google Tag Manager in particular). Also, I will mention drawbacks as well.

Before we continue

If you want to learn more about server-side tagging, take a look at this tutorial. Also, you can watch a video below:

And if you want to properly learn this topic (e.g. how to use it for Facebook Conversions API, how to send GA4 events, etc.), take a look at my intermediate/advanced Google Tag Manager course.

And now let’s go back to the main topic.


Benefits of server side tagging

There is a bunch of benefits that you can get from server-side tagging. I will mention only the biggest ones (in my opinion). If you want to learn more, check Simo’s blog post.


Reduced load on a page

When a web page loads, it has to download and process a lot of resources. As it was proved by my various experiments, JavaScript snippets that you add for analytics/marketing purposes can significantly slow down your site.

Even if the script is loaded asynchronously (which is pretty much a standard these days), it still slows down your site.

Now, imagine this: instead of loading dozens of different scripts on your website, you could have just several of them. Those scripts would be sending data to your server-side GTM container and from there, the container would modify the data according to your configurations and then send it further to more tools/platforms you are using (analytics, marketing, CRM, you name it).

However, this adds an additional level of complexity because you will need to configure how the data should be transformed, etc. At the moment, that is not an easy task — you will need to learn how to code JavaScript, understand how server-side tagging works from a technical perspective, be familiar with cloud platforms, etc.

Hopefully, in the future, the community will offer some plug-and-play templates that will do the hard work for you and you will just need to click some buttons/checkboxes, etc., and launch without too much of a hassle. Hopefully.


Control what kind of data is sent to vendors

As I have mentioned in one of the previous chapters of this blog post, JavaScript libraries loaded on a site track not only what you instruct them to do. They can collect some additional info like about the device (like screen size), the page (like page URL, page title), etc.

Those libraries that are related to advertising and cross-site tracking will collect everything they can to identify visitors with higher precision. This includes fingerprinting, cookies, etc.

From a privacy standpoint, that is not something you would want as it introduces leaks of personally identifiable information (PII). With server-side tracking, you can control what is sent to those vendors.

Here’s an example:

You have some custom-built JavaScript library that is collecting data about visitor behavior on your site
That library sends the data to your server-side Google Tag Manager container
You configure that container to send the received data to:
Google Analytics
Facebook Pixel
Google Ads

In this case, none of these 3 analytics/advertising platforms can get any additional data about the visitor except what you send to them. If you send the user ID, then that ID is delivered. But optional data that usual JavaScript libraries could have accessed on a website are now out of reach.

Why? Because Facebook Pixel in this setup is communicating with your cloud server. The visitor’s browser data cannot be reached.

If your custom JS library on the site is collecting some PII, you can process the requests in the server-side container and remove/hash it.

Reduce the impact of ad blockers

Here’s a situation: you got consent from a visitor for analytics tracking but that visitor is using some adblocking extension. In addition to ad blocking, that extension also blocks all the requests to That’s how your Google Analytics tags were supposed to send data to GA servers.

If the request is blocked, the data is not transferred.

With server-side tagging, you could create a custom subdomain to which you can send the data, e.g. On the other end, a GTM server-side container is waiting for the data. Once it is received and processed, the container sends the data further to Google Analytics.

At the moment, ad blockers do not block requests that are sent to domains like analytics.yourdomain.comWho knows what will happen in the future but right now this would work.


Extend the cookie expiration on Safari (ITP)

Intelligent Tracking Prevention (ITP) is a collection of privacy-enhancing features in the Apple Safari browser (but also affects more browsers on iOS). There are many things that are affected/limited in order to prevent cross-site tracking but the one that I’m going to talk about right now is cookie expiration.

If the 1st party cookie (meaning that it can be accessed only on your site) is stored in a visitor’s browser by JavaScript, that cookie will expire in 7 days (in some cases, the limit is 24 hours). Even if that JavaScript is completely custom, built in-house, and is not related to any 3rd party vendor, that cookie will expire in 7 days (unless a visitor keeps revisiting your site and that cookie keeps being updated).

At the moment, this limit can be avoided if the cookie is stored from the server-side. In other words, if a server (that can be accessed via your domain) stores a cookie in a visitor’s browser, its expiry date is whatever you configured it to be (e.g. 2 years).


Other benefits

The aforementioned three benefits are the most important in my opinion. If you want to learn about other benefits, you can watch my Youtube video.



However, not everything is perfect here. There are several drawbacks as well. Or maybe they should be called “Things to keep in mind”.

In fact, I already have a separate section for “things to keep in mind” and it contains more notes. Keep reading.


Paid solution

Don’t get me wrong. GTM server-side container is free and you will not incur any costs in most cases in the testing configuration. The testing configuration is an App Engine F1 instance class in the Standard environment.

But if you want to run it on a live website that is getting some decent traffic, you will need to open your wallet.

No, that’s not because the GTM container requires some premium GTM subscription. However, you need to host that server-side container somewhere. And that’s where $$$ must be spent — Google Cloud Platform.

In the production configuration, each server costs approximately $40 / month (USD). Each server is an App Engine instance with 1 vCPU, 0.5 GB memory, 10 GB disk in the Flexible environment. It is recommended to run a minimum of 3 servers to reduce the risk of data loss in case of a server outage. Hence, that’s at least $120 USD/month.

The more data you track/process, the higher the price will be.

You can also use other servers (by doing a manual setup).


Not for everyone

In order to start working with server-side tagging in Google Tag Manager, you will need to become even more technical (or hire someone who is experienced in analytics development).

If you thought that GTM already requires a lot of technical topics (spoiler alert: it really does), then from now on, the rabbit hole becomes even deeper.

That is why I think that many businesses will not start using the server-side any time soon. Some due to complexity and lack of access to technical skills, others due to increased costs (while not understanding/seeing the possible benefits).


Benefits of Server Side Tagging: Final words

Server-side tagging is definitely a very powerful solution that can make your data more accurate. However, it requires more technical knowledge (than regular client-side tracking) and will cause your business additional financial costs.

Thus you should weigh the pros and cons of this before diving deeper into server-side setup.

In my opinion, very small (or just starting) businesses are ok without it. But once you start depending more on data and getting value out of it, server-side tagging should be added to your tech stack.

The post Benefits of Server Side Tagging (with Google Tag Manager) appeared first on Analytics Mania.

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