Fingerprinting in Marketing: Tracking Behaviour Without Cookies

As digital privacy regulations tighten and browsers restrict third-party cookies, marketers are turning to alternative techniques to monitor user behaviour. One of the most prominent among these is fingerprinting — a method that creates a unique identifier based on a user’s device and browser configuration. This article explores how fingerprinting works, how brands use it, and raises important ethical questions about its deployment in 2025.

What Is Fingerprinting and How Does It Work?

Fingerprinting is a method of identifying users online by collecting and analysing a set of characteristics from their device and browser. These may include screen resolution, installed fonts, operating system, browser version, time zone, and more. Unlike cookies, which require permission to store information on a user’s device, fingerprinting is passive and difficult for users to detect or block entirely.

This technology allows companies to build a unique “digital fingerprint” for each visitor, which can persist even when cookies are deleted. While not infallible, it offers an effective way to recognise returning users across sessions and even different websites, depending on the implementation.

Since fingerprinting doesn’t rely on storing data locally, it operates within the bounds of current cookie laws, though its ethical standing remains heavily debated in legal and marketing circles.

Real-World Use Cases of Fingerprinting

In 2025, many marketing teams use fingerprinting for audience measurement, fraud prevention, and personalisation. For example, advertising networks may employ it to avoid counting duplicate visitors, especially in a cookieless environment like Apple’s Safari or Firefox. This ensures more accurate reach and frequency metrics for campaigns.

Fingerprinting is also instrumental in fraud detection. Banks and payment providers monitor unusual device fingerprints to spot potentially unauthorised access or transactions. Similarly, online stores use it to track suspicious behaviour such as rapid multiple purchases or bot-like browsing patterns.

Another use case is personalisation. While controversial, some e-commerce businesses use fingerprinting to recognise returning users and tailor content or promotions accordingly — even without asking for login credentials.

Ethical Concerns and Regulatory Response

Despite its usefulness, fingerprinting raises significant ethical questions. The primary concern lies in its covert nature: users are often unaware that their actions are being tracked without explicit consent. This undermines transparency, a key pillar of modern privacy regulation like the GDPR and the upcoming ePrivacy Regulation.

Another issue is the difficulty in opting out. Unlike cookies, which can be cleared or blocked, fingerprinting data is generated from device properties — something users cannot easily modify or control. This creates a power imbalance between users and data collectors, where individuals lack agency over how their data is used.

Regulatory bodies across Europe have expressed concerns over this technique. In 2024, several national data protection authorities initiated investigations into companies employing fingerprinting without proper legal justification. The European Data Protection Board has recommended that fingerprinting should be treated as personal data and subject to consent requirements.

Legal Compliance and Best Practices

To use fingerprinting ethically and legally, brands must follow strict guidelines. First, they need a legitimate legal basis, such as explicit consent or legitimate interest under GDPR. Consent must be obtained through clear, informed opt-ins — not hidden in long privacy policies.

Transparency is crucial. Companies should explain in plain language what fingerprinting entails, how it’s used, and offer meaningful control options. This includes alternatives to tracking, such as anonymous analytics or differential privacy tools.

Finally, data minimisation principles should be respected. Only the necessary attributes should be collected, and data should not be retained longer than needed. These steps not only ensure compliance but also help build trust with increasingly privacy-conscious users.

The Future of Fingerprinting in a Post-Cookie Era

As third-party cookies continue to be phased out, the industry is actively exploring replacements — some of which rely on fingerprinting. For instance, Google’s Privacy Sandbox initiative includes the concept of browser-level identifiers, which aim to preserve privacy while enabling advertising functionality. However, critics argue that this is just fingerprinting by another name.

In parallel, new privacy-enhancing technologies (PETs) are being developed to balance marketing goals with individual rights. Federated learning, on-device processing, and contextual targeting are being promoted as alternatives that do not require unique identifiers.

In this evolving landscape, marketers must weigh innovation against ethical responsibility. While fingerprinting may offer short-term benefits, long-term trust can only be sustained through transparency, choice, and respect for user autonomy.

What Brands Should Focus On in 2025

Brands should reconsider their data strategies and prioritise privacy as a competitive advantage. This involves not just complying with laws, but also aligning with user expectations. Offering clear privacy controls, opting into transparency, and avoiding dark patterns are now basic expectations from informed users.

Marketing leaders are encouraged to invest in ethical data collection methods and advocate for industry standards that protect consumers while supporting business goals. Collaborating with privacy tech providers and joining cross-industry initiatives can position brands as forward-thinking and responsible players.

Ultimately, success in the cookieless future hinges not on technical tricks, but on gaining genuine user trust. Fingerprinting may be one piece of the puzzle, but it must be used with care, honesty, and accountability.