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GDPR - What happened?

GDPR - What happened?
This article contains

GDPR - What happened?

In this article we look at the effect GDPR has had on the tracking landscape,
online advertising in Europe, and provide a set of recommendations for machine readable legislation.

GDPR: A primer

Having been a hot topic of discussion for at least the last 2 months, it is unlikely that GDPR needs an introduction. So in brief: the regulation applies to the processing of personal data of European citizens. Companies engaged in such processing activities are subject to compliance, regardless of whether or not they operate in the EU.

An important aspect of the regulation is the pressure put on companies to obtain consent from their European users for the processing of their personal data. This is why prior to May 25th, 2018 there was a surge in emails in your inbox, and it's also the reason for the numerous popups you see when visiting websites.

GDPR was announced two years before it came into force, and it was not the overhaul of privacy legislation one could believe it was from reading the press. In fact, GDPR came as a major update of the previous EU Data Protection Directive which has been around since 1995. Designed to harmonize the data protection legislation in the EU, and catch up with technological progress in the last 23 years, GDPR comes heavily loaded with legal language that many have found hard to navigate. Daphne Keller of the Standford Center for Internet and Society said "The final GDPR text is riddled with ambiguous passages", suggesting that the ones who will benefit the most from GDPR are data protection lawyers.

So, what happened? This is the question we are all left with. We will be using WhoTracks.Me data to make sense of the effect of GDPR on the tracking landscape in the web and on online advertising, the behemoth of third party services on the web.

Tracking Landscape on Websites

We take 2000 websites profiled on WhoTracks.Me and compare the tracking landscape in these sites as a function of the origin of the users visiting. We want to compare the EU, subject of GDPR, with the US.

Merely looking at the average number of trackers per page for each category of site being visited reveals a general downward trend in Europe. The opposite is true in the US. The blue area indicates the average number of trackers across categories.

In fact, if we look closely, since April 2018 the average number of trackers per page in the EU has dropped by almost 4% while in the US it has increased by 8%.

If we take the top 2000 domains visited by European residents, and check how the average number of trackers per page by the category of the website, we notice that there as been a reduction in the number of third parties almost across the board.

The reduction seems more prevalent among categories of sites with a lot of trackers. We see a 7.5% reduction in the average number of third parties per page from April to July in News websites. This is in the same direction as what was identified by a study published last month by the University of Oxford. They looked at news websites, and found that the number of cookies set on page decreased on average by 22%.

Some websites, like The Los Angeles Times, interrupted their operations in Europe, others decided to offer text only versions of their websites if the user does not consent to sharing data with third parties, like What we are certainly observing is a rise in the usage of consent management tools, for which we wrote about in more detail back in June.

Third party services: the winner takes it all

Both the most lucrative, and the most pervasive of all services performed by third parties is online advertising - the 'fuel' that keeps a large part of the web running.

Online advertising in 2018 is estimated to be a $270 billion market, and expected to grow by more than 20% in the next two years. This is the market that third parties are competing for, and when the prize is so high, worries over GDPR having regressive effects on competition are understandable. As in most markets, the presence of monopolies is something regulators try hard to avoid.

The question is then: Has GDPR, designed to enhance user privacy in the web, had any adverse effects on competition?

At present, has profiles for more than 1000 trackers, out of which about 200 are classified as advertising services. For each of these trackers we have data on what percentage of the measured web traffic we have observed the tracker to be loaded - reach, as well as what percentage of websites the tracker is present on - site_reach Monitoring reach and site_reach gives us interesting insights into the structure of the market these trackers operate in, as well as their relative market share. Using data, we can do that at scale. Each month we have on average about 300 million page loads and more than half a million websites.

reach is defined as proportional presence across all page loads (i.e. if a tracker is present on 50 out of 1000 page loads, the reach would be 0.05). Value is a float between 0 and 1.

site_reach is defined as presence across unique first party sites. e.g. if a tracker is present on 10 sites, and we have 100 different sites in the database, the site reach is 0.1. Value is a float between 0 and 1. 

If we rank each tracker by its reach, and measure changes in reach since April, we notice that in Europe, most advertisers appear less.

The same trend persists when we look at site_reach.

Google's advertising services have maintained their market share, while other advertisers across the board have lost reach. There could be several reasons to explain Google's favorable state post GDPR:

  1. Resources thrown at compliance: Google and other big companies have had significant resources dedicated to compliance.
  2. Google acts in the capacity of a gatekeeper, hence it is conceivable to assume it may have used that position in punitive ways. Reports indicate that Google could have encouraged publishers to reduce the number of AdTech vendors.
  3. Websites owners trying to minimize their exposure opt for 'safer choices', dropping smaller advertisers that may have a harder time proving compliance.

Using a tracker's reach as a proxy for market share, we measure that GDPR may have had regressive effects on competition in the online advertising space in Europe.

Recommendations for GDPR 2.0

GDPR has had a measurable impact on advancing the rights of European citizens on the web. We believe one of the most important contributions of GDPR is the increased transparency on how personal data is moved around, as well as the management of consent from the user, and think GDPR 2.0 should strive to be machine-readable as opposed to human-readable.

GDPR came as an update to the EU Data Protection Directive, primarily because the evolution of the web in the last 20 years rendered the old regulation obsolete. Human Readable is not the way to design a law that aims in large part to regulate interaction in the web. The design of the tools meant to empower users are left to the service providers, whose incentives don't exactly align with that of the users. This can give rise to deceptive interfaces and UX patters, designed to exploit human cognitive biases.

What we need, is a GDPR 2.0 that pushes for machine readable standards, giving rise to user-focused solutions, simple, non-deceiving interfaces, thus creating an industry of privacy and compliance, where technologists keep other technologists in check.

Here are our recommendations:

  1. /privacy-policy.txt - require websites to host the privacy policy in a standard location of the sitemap. At present, identifying the location of the privacy policy of a website is not as straightforward as one may hope. Last year as part of the Mozilla Global Sprint we built Privacy Bot, which aimed to gather, persist and analyze privacy policies. One of the challenging problems we had to solve, was identifying where the privacy policy was hosted.
  2. /third-parties.json - provide a structured list of third parties present on the site, the service being performed by them, list of data points they have access to (e.g. IP, user agent, pages visited on site ... ), and default state of consent. This would enable browsers to assume the role they should have had baked in: a unified control center for the user to manage consent. This is especially important given the rise of deceiving UX patterns we are increasingly used to seeing in websites these days. There are standards that can be built upon, like the Content Security Policy, and the Do Not Track Standards, which are widely adopted by browser vendors. A similar effort is /ads.txt, initiated by the iab techlab, aiming towards a mechanism to define authorized sellers for web content from the perspective of the domain owner.
  3. /dpo.json - increase oversight of the Data Protection Officer, detaching the role further away from the organization. Provide machine parsable details of the DPO, for users to be able to reach out more easily, as well as providing incentives for the establishment of a new market around privacy management.
  4. /incidents-and-cases.json - Data Incidents reported have increased as a consequence of GDPR. This information should also be made available to the public. The web is currently built and operated largely on trust. As such, transparency over the amount of incidents a given website or service has had to report is very important. Furthermore, provide a list of the open court cases involving the mismanagement of personal data the company is involved in.


In Europe, GDPR has thus far had a measurable impact in reducing the average number of trackers websites put in their pages, while in the US the opposite is true. The increase in transparency benefits users as they enjoy an increased control over their data, but the UX of the services managing that consent does not always have users' best interest in mind.

On the other hand, in Europe GDPR has led the online advertising market to become more concentrated, as the majority of advertisers lose market share. If this trend persists, it is possible that GDPR is having adverse effects on competition. For users this means that while the number of third parties asking for access to their data is decreasing, a tiny few are getting more of their data.

To Regulators, and especially the supervising authorities responsible for the enactment of GDPR, we think you should strive for creating incentives for industry players to keep each other in check, thereby creating a market for privacy. The only way this can be achieved is by pushing for a machine readable legislation that enforces standards.