BlockAdblock and The War on Ads

A leading anti-adblock technology for defending publisher ad revenue, featuring polymorphic code and a unique defense strategy. Prior to selling BlockAdblock, it protected more than 11,000 publishers worldwide. Ad blocking is a persistent and critical problem for publishers. Beyond just building the technology, I blogged extensively about its broader implications and solutions until BlockAdblock’s acquisition in 2017.

The trouble with ad-blocking

BlockAdblock was always a contentious project, and I received more than my share of Internet-hate for building it. Adblock users to this day, feel entitled to free content and the fruits of the publishing industry’s labor. Publishers meanwhile, remain steadfast that ads are the lifeblood of the web, and an inherent part of the social contract of free content in exchange for ad views. (A position I align with completely).

I launched BlockAdblock with the original project of creating a search engine to find ad blocking threats against specific sites. This search engine, which is still actively updated in 2025, scans for ad-blocking threats, then itemizes and explains the specific targeted filters on major ad blocking lists.

From its inception, BlockAdblock grew rapidly to become a complete anti-adblock platform. Rather than explain it all here, here are a few pages from the BlockAdblock pitch deck which sum up both the project and its strategic landscape:

What made BlockAdblock unique was its customizable nature, which allowed publishers to rapidly deploy and update anti-adblock defenses as new threats arose.

The remedies to ad-blocking aren’t simple.

Prior to acquisition in 2017, BlockAdblock played a daily game of cat-and-mouse with ad blockers — devising new defenses and detection strategies which could be rolled out to thousands of publishers using the platform. It was a constant, and unending war of Javascript skirmishes, fought behind-the-scenes and invisibly to most users — within the browser as they read their favorite sites.

To be successful BlockAdblock had to play a game not only of detecting when ads have been hidden or removed, but more importantly, anti-adblock scripts have to hide themselves from detection by ad-blockers.

To accomplish this, BlockAdblock grew daily in sophistication. It needed to adopt polymorphic code strategies to prevent detection. Custom decryption algorithms were embedded directly to complicate decryption. The script would also dynamically name page elements to prevent pattern matching, and it housed multiple fallback detection methods in case one route to Adblock detection was attacked.

With every countermeasure designed to protect publisher revenues, there came fresh new assaults from ad blockers. One week BlockAdblock would be in the lead, the next week ad blockers were blocking ads again.

2016: The regulatory shit show begins…

In 2016, the assaults on BlockAdblock became more legislative than technical: Privacy policy advocate Alexander Hanff, made the absurd, and technically misleading claim that ad block detectors such as BlockAdblock represented a “privacy violation” and warranted policy action under Europe’s GDPR.

Stunningly, later that year the European Commission (EC) agreed.

Here’s MIT’s Nieman Lab’s coverage of that shameful mischaracterization and even more shameful EC decision.

I won’t get into the weeds here, but as I stated to NiemanLab’s Ricardo Bilton in the article above, analyzing browser behavior is not at all the same as accessing user’s “stored information”. By Hanff’s contorted logic, a simple CSS media query would constitute a violation of the GDPR as well.

My full blog-post response to the issue is still available here.

Hanff still continues to play his game of technological misrepresentation to this day, going after YouTube in 2023 for their entirely legal detection of ad blockers.

Today

Today, the public-facing BlockAdblock site still exists — although the anti-adblock tech there is no longer updated. Mostly the site exists to house the Adblock Search Engine I developed. The search engine allows publishers to search for ad blocking threat vectors, and (hopefullly) respond accordingly.

After the acquisition process, I stopped blogging and maintaining the public-facing site. Responding to the ever changing threats of ad blocking is a project that requires an enormous amount of time and effort — and the daily war of whack-a-mole responses to ad-blockers is neverending.

Today, I continue to work on other technology solutions that protect / boost publisher revenues, such as my DomainLock, Wordmetrics and Brandsafe products. The threat of ad-blocking, while still acute, has taken a backseat to even more existential threats today.

The fight for a free, ad-supported and open web is a fight worth fighting.