Server-side Tag Management: Setting Appropriate Expectations

My first few posts in this series have established why marTech Ecosystem health matters, and shown some ways to measure the impact marTech is having on your site. One way to reduce some of that impact is to move some tags serverside.

As a brief primer for those still learning about Server-Side Tag Management: currently, most of us deploy a “client-side” tag manager (which means it runs within the user’s browser). The client-side TMS uses JavaScript to gather information from the page about the user’s journey, then send that information along to third parties in the form of pixels, iframes, and scripts.

A server-side TMS still has that client-side component- it still needs to gather information in the user’s browser. But instead of sending that information to third parties using scripts, pixels and iframes, it sends all the info in one big batch to a server, where you can then divvy it up and send to third parties using APIs.

This is a wonderful technology that will be used more and more in the future. Tealium has long had a server-side option, and now Google has GTM Server-Side and Adobe has Event Forwarding. But server-side tag management does have some limitations:

  1. This technology is fairly new. It can be hard to find documentation and expertise. And frankly, some of the tools still feel a little “beta”.
  2. Not all tags have a server-side option. Facebook is pushing it really hard with their Conversions API, but Bing doesn’t even have a way to send data through APIs yet. In my example image above, you can see that Bing has had to stay client-side while other tags moved out.
    Some tags will always need a client-side component: anything that changes the user experience needs access TO that experience as it loads. So scripts for optimization, personalization, recommendations, voice of customer… they may always need to have some part of it maintained on the client-side. Maintaining a server-side container and a client-side container does complicate things, but for now it’s the only way forward for most folks.
  3. The client-side component of server-side tracking still needs a way to identify the user as they move from page to page, and for the foreseeable future this will be done using cookies. GTM Server-Side can actually help a little with this, as you can use it to deploy HTTPS cookies that will make browsers like Safari happier. It can do this because you run the container on your own server, which does have a cost, but it also allows you to do first-party things. Adobe (and Tealium, as far as I can gather) host the server-side container themselves, which is less complicated for you to set up, but makes it so they can’t really help with the whole make-happier-cookies thing (though they certainly don’t hurt either).
  4. Server-side tag management still requires governance. Just because it doesn’t cause JS errors and doesn’t slow down your site doesn’t mean it doesn’t matter who you share your user’s data with. Server-side tracking is still subject to privacy regulations. GDPR and CCPA don’t care if you use JavaScript or APIs to share your user’s data, it just cares that you are sharing that data.

I’m not saying folks shouldn’t move part of their implementation server-side- I’m actually very excited to see this technology roll out more. We just need to approach it realistically and be as well-informed as possible before making decisions about it.

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