Glossary

Cookieless advertising

Advertising
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Written by
Erin Lutenski
Published on
June 10, 2025

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The future of third-party cookies was up in the air for quite a long time. And while we now know they won’t be completely deprecated, it can’t be denied that their quality continues to decay, with at least 55% of people rejecting cookie tracking As the online advertising ecosystem slowly weans itself from this decades-old foundation of digital advertising, marketers now face a key challenge: how to target the right audience and measure performance without compromising user privacy or ROI.

In this article, we break down what’s driving the shift away from cookies, explore all viable alternatives, and provide practical guidance on how to advertise without cookies. Whether you’re just starting to plan or already testing solutions, you’ll find clear steps to future-proof your advertising strategy.

A hammer smashing a cookie into crumbs
Smash your dependence on third-party cookies now to avoid getting left behind

Why are third-party cookies going away?

Third-party cookies are no longer as widely used due to rising privacy concerns and regulatory pressure. Because they allow advertisers to track users across multiple websites and predict user behavior without meaningful consent, third-party cookies fuel growing concerns about surveillance, the ethics of tracking user behavior, and data misuse.

As a counter to this, governments have introduced strict data privacy laws like GDPR and CCPA. At the same time, users are demanding more transparency and control over how their data is tracked across the web. Major web browsers (e.g. Safari and Firefox) have also stepped in and are responding by phasing out support for third-party cookies with the goal of reducing cross-site tracking and protecting individual user data.

The result? Advertisers can increasingly no longer rely on cross-site tracking to identify users, retarget them, or measure campaign success. That’s a major shift — but also an opportunity to rebuild trust and performance with more transparent, privacy-first strategies.

There are two main ways advertisers are likely to be affected by this change: How they target audiences with personalized ads and the measurement and attribution of their ad efforts. When combined, both contribute to overall ad performance and ROI, so the next section will discuss how to pick up where third-party data leaves off.

First-party data isn’t optional anymore

First-party data is any information you collect directly from your customers — through website activity, app interactions, or purchases. It’s gathered with consent, often via a clear value exchange (like newsletter signups or exclusive offers).

In a cookieless world, first-party data utilization is the cornerstone of any successful digital advertising strategy. Its use not only strengthens targeting precision but also simplifies compliance, since the data is collected directly with consent. The integration of this owned data into advertising platforms can unlock more efficient segmentation, personalization, accurate measurement, and ongoing customer engagement.
In fact, first-party data is considered the most critical personalization tool by 78% of businesses.
Its growing role in modern advertising cannot be overstated:

  • Targeting: First-party data lets you reach users based on real interactions with your brand, increasing relevance and conversion rates. It allows for more nuanced segmentation and lookalike modeling within privacy-compliant environments.
  • Measurement: It provides a reliable foundation for performance tracking, attribution, and campaign optimization. Platforms like data clean rooms make it possible to measure cross-channel lift and user engagement without direct identifiers.
  • Personalisation: Knowing who your users are helps tailor content, offers, and experiences that boost engagement. From dynamic email content to personalized landing pages, first-party data powers relevance.
  • Customer expectations: Users increasingly expect personalised, relevant experiences—but only if their data is handled transparently and ethically. Brands seen as respectful stewards of data can build stronger long-term loyalty.

Already now, 54% of brands rely exclusively on first-party data for personalization, citing its higher quality. Another 39% say they prefer it because it’s easier to manage, as it’s data they own. (Statista)

"The advertising industry is realizing that first-party data isn’t just a fallback — it’s a strategic advantage.” — Bettina Schatz, Team Coordinator for Sales Growth, Data Advertising, and Market Analysis at willhaben

To maximize value, brands must ensure robust data integration processes — combining web, app, CRM, and offline data — to create a unified customer view. This positions advertisers to activate insights at scale while maintaining control over their most valuable asset: their own data. We’ll elaborate more on the how-to process in the following section.

How to plan a cookieless advertising strategy

Here are five practical steps to help advertisers transition smoothly to audience targeting without cookies — while maintaining performance and privacy compliance. 

Audit your current use of third-party cookies

Map where and how third-party cookies are used across your ad campaigns, platforms, and measurement systems.

Map your audience targeting and measurement dependencies

Understand which parts of your marketing strategy rely on third-party data, and which can be replaced.

Expand consented first-party data collection

Improve your first-party data collection by offering clear value to users (e.g. exclusive content, early access, discounts). Use value exchange tactics to collect first-party data in compliant, user-friendly ways.

Implement tools that let you collaborate on and activate first-party data

Collaborate on your first-party data with publishers, retailers, or independent data partners using privacy-first tools such as data clean rooms.

"The combination of ID-targeting methods and a data clean room approach meets the challenges of a future without third-party cookies head-on.”— Ilias Ntinas, D2C Analytics & Insights Manager at Samsung

Set KPIs and prepare for new measurement models

Accept that old attribution models may no longer work. Begin testing incrementality, modeled conversions, or clean room-based reporting. Redefine what success looks like in a cookieless landscape.

Test and measure performance

Run A/B tests across different targeting solutions to track performance, iterate, and improve.

Budget and media-mix reallocation strategies

The phase-out of third-party cookies is driving a measurable shift in digital advertising budgets. Channels that previously relied on cross-site tracking are declining in efficiency, prompting advertisers to rethink their advertising strategies, reassessing where and how media investments are allocated.

Emerging trends include:

  • Increased investment in contextual advertising, as brands seek targeting methods that align with privacy standards while preserving relevance. Many are reallocating significant portions of their programmatic budgets toward contextual or semantic-based placements.

  • Growth in first-party data environments, particularly connected TV (CTV), publisher direct buys, and in-app advertising. These environments offer both scale and control, making them attractive alternatives to third-party cookie–dependent inventory.

  • Expansion of data collaboration strategies, including the use of clean rooms and identity-based solutions, to activate customer data securely across platforms and publishers.

  • Dedicated testing budgets, with a growing number of advertisers setting aside spend to evaluate performance across emerging approaches.

While earlier sections of this article focused on open internet environments, it’s important to acknowledge that walled gardens (e.g. Google, Meta, Amazon, TikTok) are still capturing a significant share of reallocated ad spend. Platforms like Google Ads benefit from vast, consented first-party datasets and native targeting tools that are largely insulated from third-party cookie deprecation.

However, this scale comes with trade-offs. Walled gardens offer limited transparency and require advertisers' trust that their data will be handled in a privacy-preserving way. For advertisers seeking to unify customer insights across ecosystems, this makes data clean rooms and interoperable solutions even more critical. These platforms offer functionality like direct publisher integrations, real-time optimization, and more — without exposing user-level data.

Effective media reallocation doesn’t mean choosing one path. It means building a balanced strategy that spans high-quality open web inventory, emerging privacy-first tools, and selective use of closed ecosystems — always with an eye on data control, performance, and regulatory alignment.

Listen to a discussion of the typical journeys advertisers take when stepping away from their reliance on third-party cookies in Decentriq’s own podcast episode about the topic:

Case study: Prospecting without third-party cookies

The challenge:
Facing the decay of third-party cookie quality and the need to reach new prospective customers, a major Swiss bank sought to enhance its digital marketing strategy. The bank aimed to drive awareness and consideration across the Swiss market for a new product launch, requiring a solution that ensured user privacy and complied with stringent data regulations.

The Solution:
Collaborating with Goldbach, a premium publisher reaching approximately 90% of the Swiss population, the bank leveraged its first-party customer data to inform its targeting strategy. To maintain data privacy and compliance, the bank used Decentriq's Lookalike Clean Rooms, which employ AI to extend campaign reach beyond existing customer overlaps without exposing sensitive data. 

The Results:
Over a five-week campaign, the bank conducted an A/B test comparing Decentriq-generated audiences to traditionally purchased segments. The results were significant:

  • 129% increase in click-through rate (CTR)

  • 57% increase in page views

  • 44% decrease in cost per page view

Read the full case study.

FAQs

What is cookieless advertising?

Cookieless advertising refers to targeting and measuring ads without relying on third-party cookies. It uses privacy-compliant alternative solutions like first-party data, contextual signals, or secure environments like data clean rooms.

Can you still target users without cookies?

Yes. You can target users using first-party data, contextual advertising, or up-and-coming solutions like Google’s Privacy Sandbox. The key is consent and compliance.

Is contextual advertising enough on its own?

Contextual advertising, also sometimes known as contextual targeting, is effective for awareness and broad targeting but lacks the precision of behavioral data. It works best when combined with other solutions that provide more specificity and thereby expanded targeting and personalization capabilities.

What tools do I need to go cookieless?

Key tools include consent management platforms, customer data platforms (CDPs), data clean rooms, and privacy-focused measurement solutions.

How do data clean rooms support advertising without cookies?

They allow advertisers to match first-party data with publisher audiences in a privacy-safe environment. No raw data is exchanged, and analysis is done in a secure, compliant way — making them ideal for targeting and measurement in a cookieless world.

Ready to rethink your ad strategy for a cookieless future?

Decentriq helps advertisers collaborate on and activate their first-party data in a privacy-safe, compliant environment — no third-party cookies needed. Our data clean rooms make it easy to collaborate with media partners, measure performance accurately, and stay ahead of privacy regulations.

Explore our advertiser data solutions.

References

Recommended reading

Post-cookie prospecting playbook

Our playbook breaks down the current options available to brands for targeting audiences on the open web — and how they stack up when it comes to reaching net new customers.

Key visual for post-cookie prospecting playbook

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