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Server-side solutions rely on the server to control and send data to third-party tools or manipulate content. This means companies can use cloud storage to manage changes for A/B and multivariate tests without the need to give third-party tools access to content in the browser. For tag management, Google Tag Manager server-side, this means greater control and security because the organisation decides what data to send to third-party tools.

With client-side tags, we have to rely on third-party organisations to protect personal identifiable information (PII) and to comply with GDPR and other data protection regulations. This can in some cases lead to leaks of PII data which can cause reputational damage.

Image of client and server

Client-side and server-side

1. Advantages of Google Tag Manager Server-Side:

Google Tag Manager launched it’s beta server-side tagging platform on 12th August, 2020. This aims to improve website performance and security by using server-side containers and tags. It allows you to remove measurement tags from your website or app and instead deploy server-side processing in Google Cloud. This offers a number of advantages over client-side solutions.

  • Faster page load speeds because of reduced JavaScript to run on the client-side.
  • Improved security because data is sent and processed in a server-side GTM container which is hosted in the Google Cloud.
  • There is reduced risk for personal identifiable information (PII) to be leaked by third-party tools because they only receive data you decide to send them. With client-side implementation, third-party tags run directly on a website and so they could gain access to information entered on a page. This is why customer experience tools like Hotjar automatically suppress numeric digits and email addresses to comply with GDPR regulations.
  • As third-party tags are placed in your server-side GTM container, you will have full visibility of what data the tags collect and when the data is sent.
  • Every time a tag is added to the container it will be necessary to confirm how it will be used. For example, which cookies will be accessed and where the data can be sent. You can also set rules to limit what tags can do.
  • Google Tag Manager server-side beta will also reduce the impact of ad blockers and extend cookie expiration in Safari. This means less data lost and improved data quality compared to client-side implemented web analytics.
  • Avoid spam traffic in your Google Analytics reports.

2. How is Google Tag Manager Server-Side Different?

  • You will need to create a new ‘Server‘ type GTM container where data is processed.
  • Events are initialized by incoming HTTP requests rather than triggers.
  • HTTP requests are actioned by what is known as a client. This listens out for incoming HTTP requests and ensures the details in event objects are compiled as required for their endpoints.
  • The GTM server-side container acts as an HTTP API endpoint so that any source which supports the HTTP protocol can initiate requests.
  • Provided the endpoint is mapped with a custom domain using the same hierarchy as the website sending the requests, this will ensure requests are categorised in a first-party context, which influences how cookies are read and written.

For a detailed explanation of how GTM server-side tagging works go to Simo’s blog – Server-Side Tagging in Google Tag Manager.

3. Cost:

Cloud storage is relatively cheap and so the main cost will be employing technical experts to implement and configure server-side Google Tag Manager. You will also need to pay for a cloud solution. This cost largely depends on how many sessions you will need to measure and so 100,000 sessions a month could cost your organisation around €100 a month.

4. Will Companies Switch to Server-Side Google Tag Manager?

For many large ecommerce and financial services sites server-side tagging offers compelling advantages to switch from client-side tagging. Improved speed and security will undoubtedly be a major benefit to these sites and could help with slow mobile response times in an ever more competitive market. Server-side tagging is available for both the free version of Google Tag Manager and Google Tag Manager 360.

As adoption rises expect templates and community solutions to be developed to assist the process of migrating to server-side tagging. We anticipate that for many small, less sophisticated sites there will continue to be a market for client-side tagging. However, concerns about security are likely to drive many larger organisations to switch to server-side tagging. IT departments will be attracted by the benefit of removing the risk of PII data being leaked and improving site performance.


Customer reviews of A/B testing solutions – A/B testing tools customer reviews – movers and shakers. 

Migrate to Google Tag Manager – How to migrate to Google Tag Manager for Google Analytics. 

Development & Testing – Create a development and testing process for Google Tag Manager. 

A/B testing tools – Which A/B testing tools should you choose?

Types of A/B tests – How to optimise your website’s performance using A/B testing.


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