Life After Cookies: First-Party Data Wins

Third-party cookies once powered the entire online advertising industry by letting advertisers track visitors across the web and retarget them wherever they went. That era is ending, with serious restrictions at both the regulatory and browser level. This article breaks down why third-party cookies are losing relevance, and how to futureproof your marketing and retention strategy with zero-party and first-party data instead.

What Are Third-Party Cookies?

A cookie is a small file that gets saved in your browser when you visit a website. First-party cookies come from the site you’re actually on. Thanks to them, websites keep you logged in when you navigate between pages, and web shops remember what’s in your cart. Third-party cookies work differently: they’re placed by an outside company, often an ad-tech provider, and they follow you across many different websites.

Third-party cookies have been the backbone of online advertising since their emergence in the mid-1990s. By letting advertising companies recognize the same visitors across websites, cookies paved the way for retargeting. That’s how, for example, you can look at a pair of shoes on one site and later see an ad for those same shoes on a completely unrelated website or on social media.

Advertisers used that same logic to auction off ad space in real time, aiming each ad at whoever was most likely to be interested based on their browsing elsewhere. This is still how a large part of the internet is monetized today, particularly among news sites, blogs and independent publishers.

Why Are Third-Party Cookies Disappearing?

Third-party cookies laid the foundations for digital marketing as we know it today. In the process, they spawned an entire industry of ad networks and data brokers. But with time, the tide turned against them.

In March 2018, the Cambridge Analytica scandal broke, which revealed that the consulting firm harvested personal data from millions of Facebook users without their consent for targeted political advertising. The scandal turned questions of data privacy from an abstract, niche concern into a high-stakes public interest issue. Two months later, GDPR took effect in the European Union following its adoption in 2016. With fines of up to 4% of global turnover, the regulation raised the stakes of tracking without permission while tightening the consent standards behind cookie compliance.

Meanwhile, some browsers had already started proactively addressing privacy concerns about third-party cookies. By 2020, both Safari and Firefox were blocking third-party cookies by default and Google announced it would follow suit. It has since abandoned the plan, instead letting users decide whether to allow cookies or not.

Today, the EU-wide average opt-in rate for marketing cookies sits at 46%, down from 54% in 2023 according to Searchlab. The country spread is wide: Germany sits at the low end with roughly 36%, while Italy sits at the high end with around 63%.

Regulatory enforcement remains strong, and the direction of travel is equally clear. For example, in September 2025, France’s CNIL fined Google €325 million and Shein €150 million in a single day, both for setting cookies without valid consent.

In the Digital Omnibus Regulation proposal published in November 2025, the European Commission suggested clearer banner UX rules to make cookie rejection as easy as acceptance. In countries like Germany, differences in banner designs account for a 14-point gap in opt-in rates – so stricter enforcement of design rules could push opt-in rates even lower still.

The Risks of Relying on Third-Party Cookies Today

With an average opt-in rate of 46%, businesses lose over half of their addressable signal in some of the largest EU markets before a single click can be measured.

In this situation, the risk of relying on third-party cookies is two-fold. On the one hand, there is the missing data itself: when a user rejects cookies, their subsequent actions are no longer trackable. Ad platforms like Meta and Google fill those gaps through statistical estimates of likely conversions using patterns from the users they can in fact track.

But because cookie consent is correlated with factors like digital literacy, consenting users are often a skewed subset rather than representative of the full customer base. Modelling all possible conversions only on this particular subset has serious implications for accuracy.

The ensuing issue isn’t a lack of data to work with, but companies taking compromised data at face value. Despite this, a YouGov survey from 2024 found that only 25% of advertisers felt ready for a cookieless world. The good news is that there are real alternatives to relying on third-party cookies and adopting them now gives businesses an edge over competitors still struggling to catch up.

First-Party vs. Zero-Party Data: What’s the Difference?

The clear alternative to relying on third-party cookies is to make the most of your zero- and first-party data. This encompasses all the information you gather directly from your customers through your own channels, such as your CRM, your email service provider or your ecommerce system. The difference between zero- and first-party data is whether customers share it proactively or passively. While zero-party data includes preference settings, surveys and quizzes, first-party data refers to purchases, opened emails, logged-in website sessions and similar recorded behavior.

The Way Forward: Thriving with Zero- and First-Party Data

The zero- and first-party data approach isn’t just a compliance-safe fallback but offers a real commercial advantage. Deloitte found that companies investing in first-party data strategies reduced their customer acquisition cost by 18%, increased their conversion rates by 27% and spend per customer by 20%. According to BCG, digitally mature brands leveraging first-party data saw 1.5x-2.9x higher revenue uplift.

What powers that ROI is straightforward: once zero- and first-party data is connected to a customer identity, it can capture behavior across your entire customer base and let you act on it at each step of the customer journey. Future Demand’s platform is built to do exactly that: turning your own data into action at every stage.

When it comes to customer acquisition, using your own data as the targeting foundation for your paid social campaigns makes your ad budget go further, because you waste fewer impressions on people who were never going to convert. Our app Wave builds that targeting from your own data and 100M+ external signals, then manages the campaign end-to-end with an average +50% ROAS increase.

When it comes to retention, engaging, upselling or winning back customers through channels you control — email, SMS or in-app — costs less than retargeting through third-party platforms. Our app Backhaul automates that process from the segmentation of your customer base to personalized messaging, resulting in average open rate increases of +50% and click rate increases of +40%.

How to Get Started with First-Party and Zero-Party Data

Building a zero- and first-party data strategy can start small and pay off quickly. Here are four ways you can get started today.

Map your entire customer journey: lay out every touchpoint a customer has with you across their entire lifecycle, so you know exactly which data you’re already capturing.
Clarify your data foundation for each step: for every touchpoint, identify what data you collect, where it lives and whether it’s ready to use.
Brainstorm campaigns you can run with first-party data: make a list of campaign ideas to put your data into practice, whether it’s a cart-abandonment email, a win-back offer or a loyalty campaign.
Identify opportunities for gathering zero-party data: consider at which moment customers are particularly motivated to tell you about what they want and expect – for example during onboarding or checkout – and add a question or two for them to answer.

FAQ: Third-Party Cookies, First-Party Data, and Zero-Party Data

What is the difference between first-party and third-party cookies?

First-party cookies are set by the website you’re actually visiting — they keep you logged in and remember what’s in your cart. Third-party cookies are set by an outside ad-tech company and follow you across many different websites, which is what makes cross-site retargeting possible.

Why are third-party cookies disappearing?

Firefox and Safari have blocked third-party cookies by default starting in 2019 and 2020, respectively. Regulation has tightened in parallel, with GDPR coming into force in 2018. EU opt-in rates for marketing cookies now average just 46%, and the EU’s proposed Digital Omnibus Regulation would make rejecting cookies as easy as accepting them.

Is Google still phasing out third-party cookies in Chrome?

No. After years of delays, Google abandoned its plan to deprecate third-party cookies in Chrome, opting instead to let users choose their own tracking preferences in browser settings.

What is the difference between first-party and zero-party data?

First-party data is information you observe from customer behavior like purchases, email opens, website sessions. Zero-party data is information customers proactively share with you, like preference-center settings or quiz answers. Both are owned directly by your business, unlike third-party data bought or tracked externally.

Is first-party data more reliable than third-party cookies?

Yes. Cookie consent skews toward certain user groups — for example, more digitally literate users are more likely to actively manage or reject cookies — so ad platforms modeling conversions off consenting users only are working from a non-representative sample. First-party data, tied to a known customer identity, avoids this distortion.

How do I start collecting zero-party data?

Add a preference center, onboarding quiz, or short survey at a natural touchpoint — like checkout or account creation — where customers are already motivated to share what they want and expect.

Life After Cookies: How to Win with First-Party and Zero-Party Data