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The impending death of third-party cookies – what does it mean for B2B marketers?

By John Woods  |  March 18, 2024

Third-party cookies have been endangered for some time. But now it’s official – the third-party cookie will go extinct in 2024. It will finally take its place in the museum of obsolete internet technologies, alongside the dial-up modem, Netscape Navigator and MySpace.

Why does this matter for B2B digital marketers?

In a nutshell: because most types of remarketing, and some other intent-based targeting techniques, just stop working without third-party cookies. So some B2B digital campaigns that have performed well in the past will have to be reworked or abandoned.

The ad platform operators are being a little coy – for perhaps understandable reasons – about exactly what the impacts will be and exactly what replacements and alternatives will be offered. So we B2B advertisers face some uncertainty in the coming months. Let me guide you as best I can through what’s happening, when it will happen, and what you should plan to do about it.

Disclaimers: as always, we offer this information in good faith but nothing in this article should be construed as legal advice. And there are a lot of uncertainties here and things might change (for instance if regulators intervene). I’ll do my best to be definitive, but you should read everything that follows with an implicit “My best guess at the moment is…”.

What is changing with third-party cookies, and when?

Google has announced that the Chrome browser will block third-party cookies “in the second half of 2024”. So we don’t yet have a specific date, but I guess the latest possible date consistent with that announcement is 31st December 2024.  

In the meantime, Chrome is already blocking third-party cookies for a random 1% of Chrome users. This is to allow everyone to understand the impact of third-party cookie blocking and provide time for a transition. 

Chrome is the dominant web browser worldwide with around 65% of the market (see Safari (18%) and Firefox (3%) already block third-party cookies. I can’t find a definitive statement from Microsoft about the Edge browser (5% market share) but, since it shares the underlying Chromium technology with Chrome, it’s likely Edge will do the same as Chrome. So Google’s pending change to Chrome will mean we bid adieu to third-party cookies from all the mainstream web browsers, representing more than 90% of the world’s web browsers, by December 2024 (and possibly sooner). They may linger in a few obscure or out-of-date minority browser platforms, but they’ll be dead for all practical purposes come 2025. 

Will the sky fall? Are there any massive technical impacts?


There are a few scenarios where in the past a third-party cookie might have been necessary for functioning of some website component. But let’s face it: Safari has been blocking third-party cookies by default since 2020. Other web browsers (including Chrome) have offered the option to block them for many years. If there were a technical problem with your website when third-party cookies were blocked, you’d have heard about it by now. There might be some subtle behaviour changes from some components of your tech stack, but nothing major is going to stop working with your site’s core functionality. 

Of course that all assumes that you are a business using your website as a marketing channel for your own products and services. (What the online ad industry calls an “advertiser”.) It’s a different story if you are a “publisher” (providing ad-funded content) or, worse, an online ad network (providing the tech for advertisers to buy advertising and publishers to sell it). Then, yep sorry but for you, the sky is falling. See below. 

And another situation that will impact a minority of B2B marketers: if your organisation runs multiple websites on multiple domains that need to share user data via cookies for some functional purpose – for example, so that a single user profile can be used across multiple sites – then you will need to take steps. There are some special technologies (e.g. “Related Website Sets” or RWS) that are intended for these situations, and a bunch of associated complexity and uncertainty. Details here 

So just what ARE the impacts?

For most of us as B2B marketers, the main impact is that some types of remarketing, and some types of interest-based targeting, won’t work anymore. Depending on how the different ad platforms choose to handle the transition, the affected campaigns will either stop working altogether, or serve their ads in a more limited set of locations, or – arguably the worst scenario – quietly change their behaviour so that they target a wider audience of mostly the wrong people. 

Some types of targeting can survive. For example, contextual targeting – where an ad is shown based on the content of the page containing the ad – can still work within the scope a single web page. And targeting that takes place entirely within a single logged-in platform (like a social platform or behind a premium publisher’s paywall) won’t have to change. But run-of-internet remarketing/retargeting – the ads that follow you around the internet and remind you of previous website visits – and interest-based targeting can’t work without third-party cookies. And nor can some types of display advertising that are targeted using a third-party profile (offered by some social platforms, for example). 

In case it seems arbitrary why some types of targeting are going away and others are staying, it might help to understand WHY these specific techniques are reliant on third-party cookies. So let’s have a technical interlude. 

What are third-party cookies (and why are they necessary for remarketing)?

I’m gonna do my best here to be punchy but NGL – this is technical and obscure. I won’t be offended if you skip to the next section!  

Let’s start with FIRST-party cookies. They’re bits of data that are stored by a web browser in response to a request from the site that the browser is viewing. That same website can read and write the cookie data. Other websites can’t. (Hence “first-party” – the cookie belongs to the same website that the browser visited.) Typically, a first-party cookie is used to retain some state that is important to the website across pages or across visits – for example, the contents of a shopping basket.  

So if I visit, I might receive a first-party cookie like this: 

And if I separately visit then I might receive a separate first-party cookie like this: 

Other websites can’t access the data in the first-party cookie, the browser doesn’t allow it. So first partycookies can’t be used for sharing data across sites: 

Now you might already have a clue how third-party cookies are different. When a web browser visits a site, the site may ask for data to be stored in, or read from, a THIRD-party cookie. That cookie data is sent to a different site that may have no relationship at all with the site that is being visited.  

So here I am on and that site uses a third-party cookie on Data can be sent to, and read from, that cookie like this: 

Note that I’ve not deliberately visited at all here. As the user of the browser I probably don’t even know that website exists. Access to and the exchange of data in the associated cookie is hidden away in the background of my browsing session.  

Subsequently, I visit and I’m a bit surprised to see an ad for AcmeAlternativeArchitects! That remarketing strategy is possible because the two websites I visited, and, are behind-the-scenes sharing data about my browsing history via the third-party cookie on, like this:  

Remember – in this scenario I’ve never explicitly visited and I probably don’t even realise that it exists. 

In today’s online advertising environment there are a LOT of different ad networks who are all interested in profiling and tracking users. So many websites set and read a LOT of different third-party cookies. This is what leads to privacy notices like this one: 

Because third-party cookies can share data about my browsing history across multiple sites, they can be used to drive some powerful marketing strategies, including: 

  1. Remarketing, where I see an ad for a website that I previously visited (perhaps even for a specific product from that site); and 
  2. Intent-based targeting, where my browsing history is analysed in more general terms (for instance, to infer that I might be interested in booking business travel to Australia) so that advertisers can show me products or services related to that trip. 

You can perhaps see why third-party cookies give rise to privacy worries. 

Google’s upcoming change to Chrome will act to stop this data sharing by changing the way the browser works. So in the future, requests to read a third-party cookie will just be blocked: 

Although existing third-party cookies will still hang around on users’ browsers, they won’t be accessible and there won’t be any way to use them to target advertising (or, indeed, for any other purpose). 

What will happen to our ad campaigns when third-party cookies are blocked?

Remarketing and other campaigns that rely on third-party data on display ad networks will not be able to work in their current form once third-party cookies go away. 

There might be replacement technologies of a sort. At the time of writing there are ideas around to offer something a bit like display remarketing, for example, but without the use of cookies. These ideas are still evolving, and the ad platform companies haven’t yet been explicit about how they will handle the transition to any new technical approaches. They’ve some understandable reasons for that: 

  • Some ad technology companies (like some specialist third-party ad networks) may fear they will be very badly affected by this change, to the point where their business model may no longer be viable. They may be hoping for a reprieve (e.g. if the competition regulators intervene) and certainly don’t want to scare off their customers prematurely. 
  • Other ad platforms (notably the big platform/audience owners like Google, LinkedIn and Meta) won’t be so badly affected, and may even benefit in some cases (because e.g. remarketing inventory will shift inside the “walled gardens”), but they are keeping their options open about exactly how they are going to handle the transition until the regulatory aspects are clearer. 
  • Some technology companies are working on alternative ways of targeting ads that will work without third-party cookies. Google in particular, with some partners, is actively working on alternatives to third-party cookies via an initiative called “Privacy Sandbox”. But no one is being very forthcoming with details here. Perhaps that coyness reflects a desire to avoid premature scrutiny by privacy campaigners and regulators for what are likely to be somewhat controversial approaches. 
Will Privacy Sandbox maintain the status quo?

Erm, probably not. At least for B2B marketers. 

You can read about Privacy Sandbox here: At the moment, details are scarce. Quoting from the FAQ (as of the date of this blog article): 

So a lot of ambition and aspiration, but precious little detail so far. 

In early iterations of Privacy Sandbox, Google has trialled a number of technologies including “FLOC” (Federated Learning of Online Cohorts). These use aggregate data (combining the browsing patterns from many individuals) to avoid individual privacy concerns. Another approach is called “Topics” and involves a form of contextual targeting, where the content of the visited web page is used to infer a user’s interests in a generalised, privacy-friendly way. But there doesn’t seem to be any certainty yet about the exact techniques that will finally emerge from the Privacy Sandbox to “replace” third-party cookies. 

Without more detail I can only speculate at this point. But I can’t see how Privacy Sandbox will achieve its stated objectives of preserving individual privacy and still allow the sort of fine-grained tracking that is needed for remarketing to niche B2B audiences.  

I can believe that some privacy-preserving technique working with aggregate or modelled data could do a reasonable job of predicting mainstream consumer behaviours – for example, is a person in market for a winter sun holiday, or for a new saloon car. But the niche, specialist nature of most B2B purchases is going to be too difficult. There are millions of different B2B product and service categories, and in some cases only a few hundred individuals in market for any given category at any given time. I think it’s an intractable data science problem to model and predict all of those behaviours, without using any third-party data, in any way that is useful for ad targeting. 

So while I’d love to be proven wrong, I think it is likely that whatever emerges from Privacy Sandbox will be of limited value to B2B marketers. Don’t expect anything like a pin-for-pin replacement for third-party cookies. Remarketing to anonymous visitors is going to die along with the third-party cookie. 

What steps should I take now?

First off, audit your current use of remarketing and intent-based targeting campaigns and figure out which ones are going to break when third-party cookies die. Get the best from them while you can. And be ready to stop those campaigns at short notice. 

Secondly, think about alternative strategies that you might be able to use, for example: 

  • It will still be possible to target audiences based on first-party data (subject to appropriate consent). For instance your list of email subscribers can be used to build an audience for display advertising on many social platforms. Can you make more use of this? Can you grow your email subscriber base, for instance by offering a newsletter? 
  • Keep an eye on Privacy Sandbox and similar initiatives. Perhaps credible techniques that are useful for B2B will emerge. (But as I explained above, I’m not optimistic on this.) 
  • Search remarketing (“RLSA”) will probably still work in a more limited form. Can you make better use of this? 
  • Remarketing strategies that can be implemented entirely within a social platform will still work. For instance if someone views your videos on LinkedIn, you can remarket to that person ON THE LINKEDIN PLATFORM.  
  • Contextual targeting techniques that target ads within the scope of a single web page, based on the content of that page, will still work. And we might see some innovation here from the ad networks. Be on the lookout for new contextual ad strategies for B2B use cases. 
  • Some less mainstream B2B targeting techniques use IP addresses instead of cookies. (Typically to target users on the internal network of specific companies.) These will continue to work. If the targeting options align with your campaign objectives, you might  be able to use these approaches. 

You might notice a theme here – internet-wide display networks won’t be able to offer remarketing, but the search engines and social platforms will still be able to offer remarketing within their own “walled gardens”. So an unfortunate consequence of the demise of the third-party cookie is a shift of power in favour of the large platform owners like Google, Meta and LinkedIn.   

First-party data strategies – just good old-fashioned B2B marketing

It’s arguable that third-party cookies have made B2B digital marketers a bit lazy. In a world where our ads can follow anonymous prospects around the internet, we didn’t need to try so hard to build relationships. Those days are ending. 

However you feel about the demise of strategies that rely on third-party cookies, it’s no bad thing to brush up your first-party data strategies. Having an explicit, opted-in marketing relationship with your desired audience – based on data that you own and control – is valuable in so many ways.  

Think about these aspects of your marketing mix: 

  • Do you have an email newsletter with compelling content? Do you promote it strongly at the top-of-funnel touchpoints? And via appropriate social channels? 
  • Do you have compelling “lead magnet” content that is good enough to be gated, so that it can capture contact details with marketing consent? 
  • Do you make good use of offline strategies to build your subscriber base? For example, if you use outbound telemarketing, can those calls be used to gather email subscribers? 

Even quite small changes, for example making a newsletter signup function a little more prominent on your homepage, can over time make a big difference to the growth of your first party data. And in the cookieless future, the quantity and quality of our first party data will increasingly determine our success or failure as B2B digital marketers. So it’s a great time to bring fresh energy and focus to your data strategies. 

Need help?

If you’re worried about the impacts of this change on your B2B digital marketing strategies, please feel free to get in touch. And watch this space – we’ll keep you updated via this blog and our newsletter as we learn more about some of the areas that are currently uncertain.  

Some FAQs

Q: Does this mean I don’t need to worry about cookie consent anymore? 

A: Absolutely not. GDPR and similar laws worldwide still apply to cookie use and you need to take the necessary steps to be compliant. Your site will still be setting and reading first party cookies, and they need consent. And even if Chrome and most other mainstream browsers are blocking third-party cookies, you still need consent for any legacy or niche browsers that work with third-party cookies. However you COULD take advantage of the fact that third-party cookies are going away to simplify your consent handling somewhat – there’s no need for those cookie warnings about “we and our 258 advertising partners value your privacy” if you’re no longer sharing cookies with advertising networks. So consider removing those advertising tags, and stripping back your related privacy messages, once third-party cookies go away. For information on cookie compliance see our blog article.

Q: Will Google Analytics and other tracking technologies stop working? 

A: No. Google Analytics and most other sensible and ethical tracking technologies have used first-party cookies for a long time. They won’t be impacted by the disappearance of third-party cookies.  

Q: Will programmatic and ABM strategies be impacted? 

A: Yes. These terms cover a number of different technical approaches. So they will be impacted to different degrees when third-party cookies are retired. You’ll need to look at the details of individual programmatic and ABM campaigns to assess the likely impact. But it’s likely there will be a significant impact. 

Q: What about advertising and targeting within apps, not websites? 

A: It’s different. And it’s complicated. Too complicated to get into here. In general, apps are less regulated and less dependent on browser functionality. So they are likely to be less impacted by Google’s pending change. 

Q: I’m not sure whether any of my existing campaigns are going to be impacted by this change. Can I safely just leave them running? 

A: We can’t be sure about that yet. In the past, some ad platforms have made “stealth” changes to targeting options that have made running campaigns behave in very wasteful ways – for example this change So I don’t think it’s safe to assume that your existing campaigns can be left to run. We’ll be keeping a close eye on how the ad platforms handle this change. Watch this space. 

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