What Is the Difference Between Server-Side Tracking and Client-Side Tracking?

Alight Analytics Alight Insights

Server-side tracking might be one option for measuring marketing performance going forward.

Server-side and client-side tracking are two different ways that marketers can monitor how people are interacting with their websites and apps. 

For years, client-side tracking has been the No. 1 method that marketing platforms use to see if a digital ad led someone to visit an advertiser’s website. Client-side tracking also helps advertisers target and retarget audiences across the web.  

That may be changing, though, as Apple, Google and other technology platforms enforce new rules that make it harder to use client-side tracking effectively. 

In this post, you’ll learn how server-side and client-side tracking work – and why a server-side approach may be a better fit for a cookieless future. 



Understanding the Client-Server Model

When someone visits your website, they’re really downloading copies of specific pages and assorted files from the server hosting your site. Then your visitor can open those pages in their browser, app or mobile device. 

This is an example of the client-server model of computing. Clients (like your browser) request data or files from a central computer that sends (or serves) them to the client device. 

In many cases, your website visitors aren’t just downloading pages from your website. They’re also downloading cookies to their device. The cookie is just a small text file that lets the server remember that specific device or user, as well as what pages they visited, when they visited and if they completed any forms, among other information. 

How Client-Side Tracking Works

Let’s say you visit a news site and are served an ad for shoes. In the process, you probably downloaded a cookie, too, from the ad network that placed the ad. 

So, if you visit the shoe company’s website later, the ad network can say its ad helped generate that visit. And when you visit other websites, the ad network can keep serving you ads for more shoes. It’s all because that cookie lets the ad network “remember” you. 

These types of cookies use client-side tracking. Data is sent directly from the user’s browser, app or device back to the ad network’s server. It’s called “client-side” because the action is happening on the client end of the client-server model. 

Client-side tracking has fallen out of favor because it relies on third-party cookies. This type of cookie is created by “third parties” that usually aren’t related to the websites they’re hosted on. As a result, the average person doesn’t know who might be tracking their behavior online. 

Third-party cookies can be used to create incredibly detailed profiles of users across multiple websites. While that’s great for advertisers who want to target highly specific audiences, privacy advocates and a growing number of government regulators say it’s a huge infringement. 

Big players like Apple, Mozilla and Google agree. They each have either ended or plan to end support for third-party cookies in their browsers. 

How Server-Side Tracking Works 

One alternative to client-side tracking? Server-side tracking. 

Server-side tracking uses first-party cookies — cookies that are created by the website or domain that a user is visiting (aka the first party). First-party cookies let website operators personalize their sites for visitors and gather essential analytics on website use. 

Unlike third-party cookies, first-party cookies only send data back to the server of the domain or website that created them. They aren’t stalking you around the web, so they’re viewed as being more supportive of user privacy.  

But once that data has been sent back to the server? 

The website server can share data and conversion activity with an ad network like Facebook or Google, server to server. It’s called server-side tracking because the action is happening in the server, not the user’s browser. 

That first-party-generated information can help the ad network say that User X saw one of their ads and later converted on the advertiser’s website. 

Server-side tracking hasn’t been as popular because it’s more technically demanding to execute than client-side tracking is. That might be changing, though, as ad networks create online gateways that make it easier to set up a server-side approach. Facebook’s Conversions API Gateway is a good example of this.  

Server-side tracking doesn’t restore all of the functionality that’s being lost with third-party cookies. But it still gives marketers the ability to produce an accurate count of the conversions that their digital ads are creating. 

Need Help Planning for the Cookieless Future? 

You can still get the data you need to measure, optimize and predict marketing performance. ChannelMix’s end-to-end solutions use first-party tracking to produce attribution, cross-channel reporting and more. Schedule your demo today!