Sgtm

Thanks to Giovani Ortolani Barbosa for reminding me about this possibility within Google Tag Manager and thus inspiring this blog post.

If you’re running server-side Google Tag Manager (SGTM), you’re probably sending your Google Analytics events directly to SGTM, where they are then forwarded to Google, Meta, LinkedIn, and any number of other vendor endpoints.

While doing so, you might have considered the possibility of only sending a part of the GA stream to SGTM, and having the rest go directly to Google’s CDN. Now, why would you consider this? Well, here are some reasons:

In this guide, I’ll show you how to add first-party cookie values client-side, which your server-side Google Tag Manager processes can then access.

You might be wondering: “Why bother?”. After all, if server-side GTM is running same-site with the website sending the requests, why can’t it just read the cookies on its own, right?

Well, true. But there are cases where the website and web server seem to be same-site but are in fact not. One such case is Shopify’s Checkout Extensibility.