Pixel vs. Server-Side Tracking in 2021


graphic of a pixelated person running

Pixel vs. Server-Side Tracking (2021)


For years, pixel tracking has been the standard marketing tool for web browsers, but is it still the best way? It’s time to revisit the pixel vs. server-side tracking debate. Here’s why changes in the ad market may call for a return to older server-side technologies.

Affiliate marketing has relied on browser-based cookie tracking for a long time. We once debated whether server-side or client-side (browser) tracking was the better option. But between the ease of setting up cookie-and-pixel tracking and some additional browser data it yields (which not all merchants even use), Team Cookie won that debate, and we’re still mostly using them today.

However, server-side tracking (also called postbacks or postback URLs) offers benefits. It allows merchants and networks to control data; conversion attribution is not at risk, even if a user deletes cookies or blocks them entirely. Server-side tracking also works much better with mobile devices, which often block cookies by default, and is safer from privacy regulation changes.

We’ll look at how these technologies work and whether it’s time to change to a server-side affiliate tracking standard soon.


person at a table working on a laptop with graphics overhead

Why Is Pixel Tracking So Popular?


Pixel tracking is probably the easiest form of affiliate attribution for merchants. It takes little effort to put a tracking code on a website, and it carries everything a network needs to identify the merchant, affiliate, and conversion.

In addition, when a browser goes to the merchant’s landing page to complete the conversion, the site fires a pixel that reads the affiliate cookie. It also picks up other browsing behavior data like other cookies, web page visits, conversions, and IP addresses. Anonymized, this is valuable customer experience data that helps merchants build more comprehensive customer persona models. However, since the information is collected without consent — or so many privacy advocates claim — it can be the target of regulations and browser makers’ privacy efforts.


two people looking at a large screen by servers

Why Is Server-Side Tracking Making a Comeback?


You probably know Google is abandoning third-party cookies — which doesn’t apply to affiliate links because they use first-party cookies. But you might have missed that Google also pledged not to replace those third-party cookies with another form of individual tracking. Instead, they want to limit targeting in the future to large “Federate Learning Cohorts” (FLoCs), but this effort has received a lot of pushback that forced them to delay their cookie phaseout to 2023. Meanwhile, Apple has adopted a scorched earth policy toward individual tracking, doing everything it can to prevent individual tracking through any app.

This impending phaseout has many affiliate marketers looking to cookieless tracking solutions, and server-side tracking may be their privacy-friendly solution.

In server-side tracking, when a user clicks on an affiliate link, the redirect page doesn’t read a cookie. Instead, it captures the click, affiliate, merchant, and link information along with device identifiers. That data is assigned a transaction ID which will recognize that device when it comes back to the website to complete the conversion.

Because you don’t get the browser info like you would from a cookie, the customer profile information is less robust. But server-side tracking works regardless of what kind of device, browser, or app the viewer uses. Because the transaction ID data is stored on the network, tracking platform, or merchant server, you’re able to connect it with future visits more accurately.

Many affiliate networks and tracking platforms offer proprietary versions of server-side tracking that work the same way but are customized to their needs. For example, Awin’s tracking optimization plugin allows “bounceless tracking“ through a proprietary master tag. Impact says its universal tracking tags cut out cookies, future-proof your affiliate program, and track “anything at any time.” CJ Affiliate has been responding to the General Data Protection Regulation (GDPR) for years with a holistic approach to cookieless tracking through event IDs that they say also meet Apple’s privacy goals.

If you want to transition to server-side tracking, there are many networks and tracking platforms that can help you do it. You just must decide how much you want to commit to their data solution and whether you can live without that browser data.


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