Brand Beware: Navigating The Nuances Of First-Party Cookies

Daniel Jaye headshotData-Driven Thinking” is written by members of the media community and contains fresh ideas on the digital revolution in media.

Today’s column is written by Daniel Jaye, CEO and co-founder at Aqfer.

As the world grapples with the impact of the coronavirus, businesses are struggling to figure out what life will look like once the pandemic is over. With COVID-19 creating delays and postponements, advertisers have learned that Google has no plans to postpone killing third-party cookies in Chrome. Third-party cookies are on the way out, but there’s confusion as to what extent first-party cookies can be used in this new era.

Browser-enforced privacy rules are bringing nuance to the previously held understanding of cookies and what was classified as “first party.” An inability to grasp these subtle differences could leave brands unjustly beholden to tech behemoths or severely injure access to their own first-party data, just as first-party data begins to accrue more value.

Much of the confusion stems from Apple’s Intelligent Tracking Prevention (ITP) and a class of cookies, issued at a brand or publisher’s behest, that were previously classified as “first party.” These cookies, written with JavaScript and often deployed on a brand’s owned-and-operated sites by a big tech player, such as Google or Adobe, are now considered unsafe and will typically be deleted after 24 hours. This limits a brand’s ability to connect consumers on their site to ad exposure beyond a single-day window, making accurate ad campaign measurement much harder.

Since these cookies have widely been considered first party up until now, this change has sown confusion across the ecosystem. Even sophisticated publishers and brand marketers are falsely under the impression that all first-party cookies now have a 24-hour shelf life.

That’s not the case, based on the ITP documentation and our own testing. Server-side first-party cookies, issued by an HTTP response, are still valid under ITP and are not subject to the 24-hour deletion rules that govern “client-side” cookies written by JavaScript code running in the consumer browser.

Why are these cookies allowed, but other “first-party” cookies are not? Think of it this way: If you received an incoming call from Bank of America, the standard safety practice is to not give out any sensitive information or account numbers. That is only to be done via an outbound call directly to your bank or credit provider. That’s basic safety against phishing.

Safari is acting much the same way. If a cookie is coming in via the HTTP request in a response from the server, then the cookie is coming from the first-party domain and not anywhere else on the web. It’s coming from the domain under the control of the publisher and/or the brand, and Safari is and will continue treating those cookies differently. Conversely, JavaScript on a webpage could and is loaded from many different parties on the web, allowing unanticipated data sharing.

The HTTP approach allows brands to recognize users outside of their site if they can read the first-party cookie in a third-party context. For example, if you have a server-side first-party cookie, you can determine if a consumer visits your site and then sees your ads later on.

Safari allows for a 30-day window for stitching together these kinds of interactions. With JavaScript cookies, brands have one day to make these connections. If they want to understand long-term exposure to ads, then they have to hope that the same consumers visit their website every day. For most brands, that’s just not going to happen.

In short, server-side first-party cookies aren’t in danger, but the JavaScript approach is unsustainable, thanks to ITP. As marketers move to first-party data collection, they can use this opportunity to wrest back control of their off-site consumer engagement data. Consumers know they are engaging with a brand’s content, regardless of whether it is owned or paid media.

Browser changes impact the ecosystem; techniques such as server-side first-party cookies are sustainable, and they build on the solid policy foundation that the brand has a legitimate interest in data about its own interactions with consumers.

Follow Aqfer (@aqferinc) and AdExchanger (@adexchanger) on Twitter. 

Enjoying this content?

Sign up to be an AdExchanger Member today and get unlimited access to articles like this, plus proprietary data and research, conference discounts, on-demand access to event content, and more!

Join Today!


  1. Andrew

    This is the best explanation of 1st party cookies and ITP that I have read. Thank you!