The role of cookies, and especially third-party cookies, is more prominent than ever in today's world of e-commerce. Professionals and online store owners rely on cookies to provide personalized user experiences, fuel online advertising strategies, and enhance their data analytics efforts. However, developments in browsers are making cookie blocking increasingly common, especially on the part of third-party services (third-party cookies). This drastically affects the ability to track traffic and target consumers, as performance campaigns become more difficult and conversions become harder to measure accurately.

The problem is exacerbated by the fact that many browsers, such as Safari and Firefox, have implemented stricter settings for blocking third-party cookies, while even Chrome is moving towards similar changes. At the same time, data protection requirements (e.g., GDPR) are forcing companies to adopt more transparent practices. In this article, we will analyze methods and strategies for reliably detecting third-party cookie blocking, explore how professionals can adapt to new challenges, and discuss how they can remain competitive in the digital marketplace.

Why blocking cookies is such a big threat

When third-party cookies do not work, online advertising and remarketing capabilities are limited, as advertising platforms cannot target specific audiences with high accuracy. This can lead to increased costs and reduced sales in online advertising campaigns.

Collecting data on visitor behavior is crucial for product development, UX improvement, or creating personalized offers. Without cookies, analytics tools remain «blind» or less accurate, affecting the quality and quantity of information gathered.

Many business intelligence (BI) systems and data analytics tools rely on cookies to reliably track website traffic and user returns. When cookies are blocked, statistics may deviate from reality, creating misunderstandings and errors in strategic planning.

How to detect cookie blocking

According to the article «Reliably Detecting Third-Party Cookie Blocking 2025» (SmashingMagazine, 2025), one of the most common ways to determine if cookies are being blocked is to test with first-party cookies. Create a test cookie directly within your domain and check whether the user's browser accepts it. Conversely, confirm whether a third-party cookie (e.g., from an advertising network) is not accepted by the same browser.

• Example: Send a first-party test cookie (e.g., “mydomain_test=true”) and, in a separate script, try to write a third-party cookie (e.g., “adnetwork_test=true”). If the first is available and the second is blocked, then the user or their browser is likely implementing third-party cookie blocking.

Since third-party cookies often come from embedded scripts or iframes, you can take advantage of how the browser loads third-party content, such as social media plugins or advertisements. If an iframe cannot store and call a cookie, the likelihood of cookie blocking is high.

At the same time, using modern tools and JavaScript APIs, you can perform data storage tests and detect whether the browser allows or denies third-party operations. Systems such as localStorage or sessionStorage can enhance this test, although in some cases they also face limitations.

Strategies for adapting to the new circumstances

A first step toward compliance is to implement cookie consent banners that comply with the GDPR and other international legislation. When you give users options to accept or reject cookies, this can strengthen trust in your brand and reduce the rates of accidental or automatic cookie blocking.

As third-party cookies are restricted, several companies are investing more in collecting and utilizing first-party data. This includes the ability to gather data from your own channels, such as newsletters, loyalty programs, and surveys, allowing you to implement personalized campaigns without the risk of cookies being blocked.

With the decline of third-party cookies, new solutions in targeted advertising are emerging, such as contextual advertising and server-to-server integrations. Advertising campaigns now focus more on page content than on the individual behavior of each visitor, while techniques such as browser-based tokens are evolving. So, consider platforms that offer a combination of data and user recognition technologies without relying solely on cookies.

Benefits of reliable cookie blocking detection

More effective decision-making: Knowing whether users have blocked cookies allows you to adjust your marketing strategy and offers.
Reduce advertising costs: By being aware of the restrictions on third-party cookies, you can better organize your advertising campaigns or switch to alternative marketing automation techniques.
Better compliance with regulations: The more transparent and targeted your data collection activities are, the better you will meet the requirements of the GDPR and other international regulations.

Practical advice for professionals and online stores

Use an upgraded cookie consent management tool to guide users toward accepting cookies on understandable terms.
Perform frequent checks of analytics tools and compare the results with other sources, such as raw server logs, to assess whether there are any discrepancies that indicate cookie blocking.
Invest in first-party data technologies: Developing loyalty programs and maintaining an up-to-date email list can help personalize content without relying solely on third-party cookies.
Maintain alternative targeted campaigns: Contextual advertising is less sensitive to cookie blocking, while it can also be combined with segment data from other sources.
Don't forget about ongoing team training: By setting clear goals and keeping your marketing and IT departments informed about developments in data protection, you can ensure that you stay ahead of the curve.

Blocking cookies is not just a technical challenge, but affects the entire value chain of an online store or business. Accurately detecting cookie blocking and adjusting your strategy are critical steps in maintaining market competitiveness, protecting your brand reputation, and maximizing your online advertising and data analytics capabilities. By implementing the right tools, such as first-party cookies, robust cookie consent systems, and modern recognition technologies, you can take advantage of the opportunities available, despite the limitations imposed by new regulations and browser developments.

Sources:

- Smashing Magazine – Reliably Detecting Third-Party Cookie Blocking (2025)

• Mozilla Developer Network, https://developer.mozilla.org

• European Commission (GDPR), https://ec.europa.eu/info/law/law-topic/data-protection_el