The Rise of Consent-based Advertising2021 PageFair Adblock ReportForeword
We are excited to present the 2021 PageFair Adblock Report, theseventh in this series. Adblocking on mobile continues its strong
linear growth, driven chieﬂy by the rapid adoption of mobile
browsers that block advertising by default. Desktop adblocking
also shows a moderate rise for the ﬁrst time since 2016, possiblyon account of more people using laptops and desktops tobrowse the web at home due to worldwide Covid-19 restrictions.
Amidst this multi-platform renewal of adblocking, one silver
lining for publishers is the growing adoption of Acceptable Ads, aframework that allows publishers to earn revenue by serving
light, non-intrusive ads to consenting users of participating
adblockers. This report is the ﬁrst to estimate the size andgrowth of this user base; in 2020, the number of users
consenting to receive Acceptable Ads crossed 200M for theﬁrst time, with 435% growth on mobile from 2019 to 2020.
We also surveyed 5,423 US Internet users about their adblockusage as well as their perceptions about ads and privacy. One
key ﬁnding from this survey is that while users value their online
privacy more than ever, 74% don’t mind being advertised to aslong as it is consent-based and preserves their privacy.

© BLOCKTHROUGH | 2021 PageFair Adblock Report

Another striking ﬁnding from our survey is that US users’ self-reported
rate of adblock usage (~40%) is signiﬁcantly greater than the 15-20% thatmost US publishers record with traditional adblock detection
methodologies. Some of that discrepancy can be attributed to survey
noise or respondent misconception as to what constitutes an adblocker.
However, we believe there is another major factor at play: the rise of the“dark matter of adblocking”; i.e. adblocking tools whose usage is hardto measure using conventional means because they block the very
technologies publishers use to measure adblock visits, and they do not
rely on the open-source EasyList blocklist. This includes network-level
adblockers, those bundled with anti-virus or VPN software, hardware
adblockers, as well as especially zealous adblocking browser extensions.
In future reports, we will seek to more precisely quantify this dark
matter. In the meantime, everything points to the conclusion that it is
growing in mass, even if we can’t see it with the naked eye.

Marty Krátký-Katz
Co-founder & CEO, Blockthrough2

Spotlight on Consent

Table of Contents
Introduction

1

In this sequel to the 2020 BT/PageFair Adblock Report , we present thelatest data gathered for global adblocking and results from our U.S.
consumer survey about adblock usage and privacy preferences.

2. Foreword
3. Table of Contents
4. Key Insights

The increasing focus on user consent has been the driver of signiﬁcantchange in the advertising industry, from privacy regulations like GDPR
and CCPA to Google’s looming deprecation of third-party cookies.

Empirical Adblocking Data

As we undertake this historical industry-wide pivot, one hypothesis we
wanted to evaluate is whether user preferences about ads and privacy
fall on a spectrum as opposed to being binary, as the industry andprivacy advocates alike have presumed. In the Ads-Privacy Preference
Matrix, we break out user preferences into nine distinct user buckets
and estimate the percentage of US users that fall into each bucket
based on their responses to our survey. We think this information will
be invaluable both for publishers trying to better understand theiraudience and adtech companies building solutions for the market.
You’ll also ﬁnd updated information on recurring themes from previous
reports, such as the growth of desktop and mobile adblocking,region-wise penetration of adblocking, and a granular analysis ofadblock countermeasures employed by the world’s leading publishers.
We hope you ﬁnd this report timely and useful.
12020 BT/PageFair Adblock Report© BLOCKTHROUGH | 2021 PageFair Adblock Report

5. Desktop Adblock Users
6. Mobile Adblock Users
7. Global Adblock Penetration
8. Growth of Acceptable Ads
9. Analysis of Adblock Countermeasures

2021 U.S. Adblock Survey Results
10. User Demographics
11. User Motivations
12. Consent in Advertising
13. Privacy Preferences
14. The Ads-Privacy Preference Matrix

Appendices15. About Blockthrough16. Next Steps
17. Methodology
18. Acknowledgements
3

Key Insights
At the end of 2020:➔

Mobile adblocking grew 10% to reach 586M users➔

Desktop adblocking grew 8% to reach 257M users

Other ﬁndings:➔

Adblock users are twice as likely to accept light, non-intrusive ads
rather than engage with adblock walls or pay for content➔

63% of top US Comscore publishers reviewed in this report wereusing some type of adblock countermeasure, up from 56% last year➔

67% of US Internet users think that the quality of advertising on the
web has either declined or stayed the same in recent years➔

User adoption of Acceptable Ads is growing fast, reaching 218M
users in 2020, with 435% growth on mobile over the last two years© BLOCKTHROUGH | 2021 PageFair Adblock Report4Desktop Adblock Users
Desktop adblock usage rebounds after a period of slight decline➔

These estimates omit users of adblockers not reliant on the EasyList blocklist; i.e.
they do not account for the “dark matter of adblocking” (see Foreword, Slide 10)➔

Following a period of decline between Q1 2018 and Q4 2019, desktop adblocking ison the rise again, growing almost 9% YoY➔

At the end of 2020, there were over 257 million
monthly active users of desktop adblocking© BLOCKTHROUGH | 2021 PageFair Adblock Report5

Mobile Adblock Users
Mobile adblock usage continues its upward trajectory➔

Mobile adblock growth is largely driven by increased adoption of mobile
web browsers that block ads by default➔

UC Browser remained the most widely adopted mobile ad blocker
despite losing a sizeable chunk of its user base in 2020 following
a ban in India; we estimate that it has 310M users worldwide➔

The Brave adblock browser grew 92% YoY
to hit 20M users in Dec 2020

© BLOCKTHROUGH | 2021 PageFair Adblock Report

6Low penetration

High penetration

Region-wise share of
total adblocking
Asia (40.6%)
Europe (29.6%)
Americas (19.2%)
Africa (9.2%)
Oceania (1.2%)

Global Adblock Penetration
EasyList-based adblockers only (December 2020)© BLOCKTHROUGH | 2021 PageFair Adblock Report7

Acceptable Ads
Crosses 200M Users
User opt-ins for Acceptable Ads continue togrow at a fast rate, especially on mobile devices
Key Findings➔ Acceptable Ads has a 93% average opt-in on desktop and mobile
devices for adblockers that support it➔ By the end of 2020, a total of 218 million adblock users had opted
in to Acceptable Ads, up 54% from the beginning of 2019
➔ Mobile opt-ins for Acceptable Ads increased by 435% in this time,from 17 million at the start of 2019 to 91 million by the end of 2020
➔ The consent mechanism for Acceptable Ads is at the browser/
extension level, eliminating the need for site-level opt-in

Analysis
The Acceptable Ads ecosystem enables publishers to engage their adblockusers with light, consented advertising. The rapid growth of the ecosystemand high opt-in rates make ad recovery via Acceptable Ads the mosteﬀective and respectful technique for monetizing adblocked inventory.

© BLOCKTHROUGH | 2021 PageFair Adblock Report8

Analysis of Adblock
Countermeasures
Last year, we reviewed the adblock monetization strategies employed by the
top 100 Comscore-ranked publishers impacted by adblocking. This year, weused the same list of publishers to re-run the analysis. 63% of them wereusing at least one adblock monetization strategy, up from 56% in 2020.

Key ﬁndings
Of the 63 publishers that take measures to monetize adblock users:➔

52 use ad recovery via Acceptable Ads, up from 49 in 2020. Only 8 ofthese work directly with participating adblockers; the remainder workwith an adtech provider who supports Acceptable Ads.

➔

9 of the top 10 Comscore-ranked publishers in the U.S. (including
Google, Verizon, and Amazon) monetize with Acceptable Ads.

➔

Blockthrough was the most popular dedicated provider, with 48%
market share among top publishers using Acceptable Ads.

➔

Only 1 major US publisher (Facebook) uses adblock circumvention.

Analysis
Last year, we reported that the top ad-funded U.S. publishers have embraced
the Acceptable Ads ecosystem as the most reliable and sustainable medium formonetizing their adblocked audience. This year, that trend continued, with amajority of US publishers now using Acceptable Ads.

© BLOCKTHROUGH | 2021 PageFair Adblock Report9US Adblock Survey (2021)
Self-reported adblock usage among US Internet users hints at “dark matter”
Key Findings➔ 40% of US Internet users claim to use an adblocker, but there are caveats (see Analysis)➔ Almost twice as many US adblock users were blocking ads on desktop and laptop compared to mobile devices

Analysis
These results are in line with other recent industry reports that surveyed US users about their adblock usage. While some ofthose 40% may be false positives, almost 90% of adblock users could name the adblocker they use, hinting at a “dark matterof adblocking”; i.e. growing user adoption of adblockers that block the very technologies publishers use to record theseusers’ visits. We estimate that the adblock rates detected by most common adblock detection methodologies only record
about 60-80% of total adblock usage. These forms of adblocking are not counted in our desktop and mobile usage graphs.

65%
61%
55%

51%

47%

48%

30%

35%

31%

28%
22%

M

F

Avg.

M

18-29
© BLOCKTHROUGH | 2021 PageFair Adblock Report

F

Avg.

The following pages
present ﬁndings
from that survey.

46%
35%

40%
Avg
Self-Reported
US Adblock
Rate

In March 2021,
Blockthroughsurveyed 5,423 US
Internet users tolearn more about
their adblock usage,
perceptions about
speciﬁc adblock
recoverymechanisms,
knowledge ofprivacy regulations,and general privacy
preferences.

M

30-44

F

Avg.

M

45-60

F

20%

Avg.

M

>60

F

User Motivations
Bad ad experiences replace security as theleading motivation for the use of adblockers

Motivation for using ad blockers
81%

To avoid interruptive/annoying ad experiences

62%

To protect myself from malware

58%

To protect my privacy

Key Findings➔ 36% of respondents said that overall ad quality on the Internet has
declined in the last few years, 31% said there’s been no change in adquality, while only 19% said that ad quality has improved➔ 37% of respondents stated that they began using an ad blocker within
the last two years; the remaining 63% have been long-time users➔ 7.4% of all surveyed users had stopped using an ad blocker
because: (1) The blocker wasn’t consistent, (2) the blocker frequently
blocked non-advertising content, and (3) to support publishers

Analysis
In the last PageFair Adblock Report to include an audience survey (2017),
security was found to be the leading motivation for the use of ad blockers. In
2021, bad advertising experiences take the top spot. Despite industry
initiatives such as the Better Ads Standard and Chrome’s ad ﬁltering updates,
the new survey data indicates that those eﬀorts have not had an immediate
impact on user perceptions of the quality of online advertising.

© BLOCKTHROUGH | 2021 PageFair Adblock Report

23%

To save device battery

22%

To save bandwidth2%

OthersMost popular adblockers in the US(users could select multiple options)

AdBlock (50%), Adblock Plus (25%), AdGuard (19%),
uBlock Origin (16%), uBlock (11%), Brave (10%),
Opera (9%), Ghostery (7%), andOthers, including Ad Remover, Norton,
Kaspersky, Blokada, Pi-hole, and Avast (11%)
11Consent in Advertising

Would you be willing to accept light, non-intrusive
advertising to support web publishers?

Adblock users are over twice as likely to consent to
Acceptable Ads as to comply with “adblock walls”
Key Findings

No (37%)

Yes (63%)➔ When asked if adblock users are willing to accept light, non-intrusive
advertising to support web publishers, 63% of respondents said “yes”➔ When presented with an adblock wall, 68% of respondents said theywould exit the website, 22% said they would whitelist the website, and5.7% said they would be willing to buy an “ad removal” pass
➔ Only 15% of respondents said that they are “likely” to purchase a paid
subscription to access the content they are looking forIf a website blocks access to adblock users, what isyour next step likely to be?
Other(4.4%%)

Analysis
Consent-based advertising (via Acceptable Ads) and messaging-based tools(such as adblock walls) are the two leading strategies publishers use to engage
their adblocked audience. Our survey demonstrates that adblock users
overwhelmingly prefer a light, non-intrusive advertising experience acrossthe Web, compared to all other strategies combined, such as complying withwhitelist requests or paying to access content on a per-site basis.

© BLOCKTHROUGH | 2021 PageFair Adblock Report

Exit the site
(68%)

Buy an“ad removal” pass
(5.7%)Whitelist the site
(22%)

12

Privacy Preferences

Do you think recent privacy regulations such as GDPR
and CCPA have improved your privacy?

Privacy takes center stage as users desire
more control over their data and how it is used50%

I don’t know what GDPR and CCPA mean

Key Findings

20%

No opinion

16%

No

14%

Yes

➔ Online privacy is increasingly important to Internet users. When
asked how much they value their online privacy, 56% of users rated it
as “extremely important” and 31% rated it as “somewhat important”➔ 74% of all users don’t mind being advertised to as long as the ads
don’t compromise their privacy and meet certain quality standards➔ Only 14% of all users we surveyed believed that privacy regulations
like GDPR and CCPA improved their online privacy➔ Cookie notices have become common ever since newer privacy
regulations came into eﬀect. 21% users report rejecting all cookies
when presented with a cookie notice by a website, while 69% either
accept all cookies or selectively accept some types of cookies

Analysis
Our privacy preference questionnaire debunks the common misconceptionthat most users dislike advertising, in reality—users are simply far moresensitive about their personal data and how it relates to advertising. Thisis also established on the next slide, where thousands of users rate theimportance of privacy and their openness to advertising on a sliding scale.

© BLOCKTHROUGH | 2021 PageFair Adblock Report

When presented with a cookie notice by a website,what action are you most likely to take?

41%

Accept some types of cookies

28%

Accept all cookies

21%

Reject all cookies

10%

Not sure

13

The Ads-Privacy Preference Matrix

We then slotted themin the appropriate cellon this matrix. It’s
immediately clear thata top concern for mostInternet users today issafeguarding their
online privacy.
Additionally, only 21%
of users dislike
advertising enough toreject it in all forms.

HIGH

Importance of
online privacy

All users perceive
advertising and value
privacy in diﬀerent
ways. We asked oursurvey audience(including adblockusers and non-adblockusers) to evaluate their
feelings about
advertising and online
privacy on a spectrum.

12%

30%

15%

Highly open to advertising,value privacy highly

Open to non-intrusive
advertising, value privacy highly

Dislike advertising,value privacy highly

9%

21%

6%

Highly open to advertising,value privacy moderately

Open to non-intrusive advertising,value privacy moderately

Dislike advertising,value privacy moderately

<1%

2%

<1%

Highly open to advertising,
do not value privacy

Open to non-intrusive
advertising, do not value privacy

Dislike advertising,
do not value privacy

LOW© BLOCKTHROUGH | 2021 PageFair Adblock Report

Dislike of advertising

HIGH

14

About BlockthroughFounded in 2015, Blockthrough is the market leader in adblock monetization. Publishers use our best-in-classtechnology to serve Acceptable Ads to consenting adblock users, with the option of using their existing
programmatic demand partnerships or plugging in Blockthrough’s demand.
Blockthrough acquired PageFair in late 2018, and this report is a continuation of the annual PageFair Adblock
Report, which was instrumental in driving industry dialogue about and publisher awareness of the state ofglobal adblocking since the launch of the ﬁrst edition in 2013.
We’re passionate believers in the free Internet and, at the same time, are adblock users ourselves. We believethat publishers have the right to monetize their content, and their users deserve an outstanding experience.
We’re also incredibly proud of our talented and hard-working team.

Next Steps
Publishers➔

Check this revenue recovery calculator to get an estimate of how much
adblock revenue you can recover or email us at sales@blockthrough.com
to learn more about our market-leading adblock monetization solution➔

Sign up to our newsletter and follow us on Twitter or LinkedIn to keep
abreast of the latest developments in the adblock-mitigation world

Advertisers➔

To learn how you can advertise to hard-to-reach, consenting adblock users
via Acceptable Ads, email us at contact@blockthrough.com

Journalists➔

Feel free to reproduce any part of this report, attributed to Blockthrough➔Email vj@blockthrough.com for media inquiries© BLOCKTHROUGH | 2021 PageFair Adblock Report16

Methodology
Calculation of Desktop Adblock Users
In our 2020 PageFair Adblock Report, the number of devices using adblock software on desktop/laptop
computers was calculated by estimating the number of monthly active adblock users that are required togenerate the number of downloads that were recorded for blocklists in each historical month.
A blocklist is a frequently-updated structured text ﬁle that contains rules about how to block ads on websites.
All major desktop adblock software works by downloading one or more community-maintained blocklists todrive their behavior. Normally they download the “Easylist” blocklist, or download a combolist, which combines
both Easylist and a language-speciﬁc blocklist. For example, “Liste_FR+Easylist” provides additional rules toblock ads on the French web. Each blocklist includes an expiry header, which tells the client software how
many days to wait before downloading a newer version. For example, given a web browser conﬁgured with an
adblock extension which is subscribed to a blocklist with an expiry of 4 days, that computer will download thatblocklist once every 4 days so long as the browser remains open. If the web browser is shut down, it will
re-download the blocklist at its next available opportunity. All of the major community blocklists are hosted by
Eyeo Gmbh (“Eyeo”), the company that operates Adblock Plus (the most popular desktop adblock software).
Eyeo therefore has 1st party access to basic web statistics about the traﬃc received by each blocklist.
This year, due to the increasing complexity involved in aggregating raw data (ﬁlterlist downloads) frommultiple sources, Eyeo instead shared their own internal estimations for the number of active users for theyears 2019 and 2020. Eyeo's internal method of estimating active devices is very conservative. They exclude
devices that installed in the counting period and devices that recently were inactive for more than 30 days. In
order to counterbalance this underreporting, we calculated the average variation between MAUs estimatedusing our older methodology and new MAU estimates provided by Eyeo for 2019. We then used this averagevariation to extrapolate MAU estimates for all the four quarters of 2020.

Calculation of Mobile Adblock Users
Whereas the majority of desktop adblocking can be measured via blocklist downloads, the same is not true
for mobile, where mobile browsers that block ads by default are the main driver of adblocking. We therefore
cannot rely only on Eyeo’s internal estimations of mobile adblocking to present an accurate estimate foradblocking on mobile. In the previous report, we calculated the number of users for the most popular mobile
adblock browsers, i.e., UC Browser, Opera, and Brave, to arrive at the total estimate for mobile adblocking.
This year, we followed a similar approach, but updated our data sources. The MAU numbers for Brave andOpera were obtained directly from their oﬃcial releases about user growth. For quarters where this data was
not available, we linearly extrapolated the known values to ﬁll missing data points. Since UC Browser does notrelease any oﬃcial MAU numbers, we explored alternative ways of estimating its active user base.

© BLOCKTHROUGH | 2021 PageFair Adblock Report

For the last report, we relied on internet populations per country and Statcounter data about device split
between devices and market share of mobile browsers to estimate MAUs for both Opera and UC Browser.
However, we found a signiﬁcant diﬀerence between the MAUs we estimated and the oﬃcial numbers
released later by Opera for those quarters. Thus, repeating the same methodology for UC Browser might
have reproduced similarly inaccurate results. So for this year, instead of combining estimates of traﬃc sharewith internet population per country, we estimated UC Browser’s active users by comparing its traﬃc share to
Opera’s, and then using Opera’s oﬃcial MAU numbers to create projections for UC Browser.
Finally, we added the MAU estimates for UC Browser, Opera, and Brave to a reduced dataset of the internal
estimates provided by Eyeo for adblocking on mobile to eliminate any potential double counting.

Global Adblock Penetration
The heatmap of adblock penetration by region was created using Eyeo’s estimates for active users and new
installations for large geographic regions at the end of 2020. In this report, we are not providing country-level
estimates for the percentage of adblock users by region for two reasons:First, as stated previously, Eyeo’s internal estimates tend to be very conservative. We are conﬁdent in our
methodology’s ability to create global estimates for desktop adblocking, but extrapolating country-level data
might have introduced too many statistical artefacts for us to be conﬁdent in our estimations. Second, themarked rise in adoption of diﬃcult-to-detect adblockers (the “dark matter” we reference throughout thereport) that do not rely on EasyList downloads would have resulted in substantial underreporting ofcountry-level penetration. With that in mind, the adblock penetration data we present in this report shows thecountry-level concentration of active users who use EasyList-reliant adblocking software only.

2021 US Adblock Survey
For our audience panel, we partnered with a leading third-party survey vendor yo target a sample size of
5,423 users to make sure that the data we collect is statistically signiﬁcant. We applied basic census controls
to make sure that both genders and all major age groups have equal representation in the survey.
For the survey itself, we used a conditional logic to steer users towards questions that are most relevant totheir speciﬁc experience with adblocking software. All users were asked a series of questions about theirgeneral privacy preferences and attitude towards advertising regardless of whether or not they currently usean adblocker. For active adblock users, we had an additional inventory of questions speciﬁcally targeting theirmotivations for using an adblocker, which devices they are blocking ads on, what they think about adblock
walls, and which adblocker they are using, etc. The last category of users, who previously used an adblocker
but stopped, were asked to share their motivation for not using an adblocker anymore.

17

Acknowledgements
Vishveshwar Jatain
Thank you to Vishveshwar Jatain for all his hard work conducting the analysis, planning, and execution of this report.
Stephan Porz
For helping us analyze and interpret the adblocking estimates that are presented in this report.
Ben Williams
For providing data related to country-level adblocking estimates and Acceptable Ads opt-ins for 2019 and 2020.
Sean Blanchﬁeld
For his feedback and suggestions related to speciﬁc parts of this report and sharing the context of past reports.
StatCounterThank you to the StatCounter team, who generously make a wealth of Internet analytics available for free.

© BLOCKTHROUGH | 2021 PageFair Adblock Report18