Client side vs Server side

Google Tag Manager Server Container
1

Hello,

We have a client who wanted to test out Client Side vs Server Side. So they had me set up a separate GA4 for SS. But after setup my SS GA4 gets less data than CS? Is that normal or is it simply not possible to make this?

We would like to tell our client that their data will get better if they only use 1 and not the other… Any proof or what can we do?

2

Hey!

Below is a reply from a similar thread:

Comparing GA4 performance in this way is bad practice and you can only by luck and very, very correct setup get normal results.
If you just add a new property and tags for it in parallel with the web - you will get bad results because GA4 is not designed to run multiple properties in parallel, especially if one of them is server-side and the other is client-side.

You may note that for using multiple GA4s in parallel there is a separate Rollup property functionality which is only available in the 360 version [GA4] About roll-up properties - Analytics Help

If you could just add a couple of extra google tags it would hardly be one of the 360’s features :slight_smile:

Also, here is an excellent article on how to try to correctly configure parallel operation of several GA4, you can estimate the number of nuances there: Build a GA4 Roll-up Property Using Server-side Google Tag Manager | by Markus Baersch | Medium

And in general there is no point in such a comparison. GA4 in server side format works as a proxy. Data is not changed in any way, nothing happens to it (unless you have specially configured it, which is usually very rarely done), requests are simply redirected further to GA.
So there is not much to compare here.

If you want a super safe transition - in GA4 client switch on JS managed cookies at the beginning, when after some time you are sure that everything is fine - switch to server managed cookies and activate the migration option. In this case everything will definitely go without problems if you don’t have problems with tag configuration.
If you have problems with unassigned/not set traffic sources when switching to server managed cookies, here is an article that describes the problems and solutions perfectly: Unassigned and not set traffic source in GA4 - Stape