Web Admin’s Bold Move: Blocking Outdated Browsers to Combat AI Crawler Onslaught

In an unprecedented digital standoff, a prominent technology blogger has taken drastic measures to protect his online content from what he describes as an “AI training data gold rush” that’s flooding the internet with automated crawlers.

Chris Siebenmann, the mastermind behind the popular Wandering Thoughts blog hosted at the University of Toronto, has implemented aggressive browser blocking measures that are catching unsuspecting visitors in the crossfire. The move comes as AI companies ramp up their data collection efforts, with Siebenmann estimating that high-volume crawlers are now using old browser user agents—particularly outdated Chrome versions—to scrape content at scale.

“I’m experimenting with (attempting to) block all of them,” Siebenmann explains in his notice to affected users. “And you’ve run into this.” The timing is significant: early 2025 has seen a dramatic surge in automated content harvesting, with many of these crawlers masquerading as legitimate users through falsified browser signatures.

The collateral damage is real. Regular readers accessing the blog or its companion CSpace wiki are finding themselves locked out simply because their browser versions trigger Siebenmann’s anti-crawler algorithms. “Most often this applies to versions of Chrome,” he notes, suggesting that even moderately recent browsers might fall victim to the sweeping restrictions.

For those caught in the digital dragnet, there’s a path forward. Siebenmann invites affected users to contact him directly through his university email address, requesting specific details including their exact User-Agent string. This level of technical specificity underscores the complexity of distinguishing between legitimate users and sophisticated AI crawlers operating in the wild.

The situation becomes even more nuanced for users of the Vivaldi browser. Due to what Siebenmann describes as an “ongoing attack,” Vivaldi users must adjust their “User Agent Brand Masking” settings to identify themselves as Vivaldi rather than Google Chrome. This requirement applies even to current Vivaldi versions, highlighting how deeply embedded the problem has become in the browser ecosystem.

Archive service users face their own set of challenges. Siebenmann has specifically called out archive.today, archive.ph, archive.is, and similar services, stating that their crawling patterns are “impossible to distinguish from malicious actors.” These services use old Chrome User-Agent values, distribute their IP addresses across widely scattered blocks, and—most concerning—some falsify reverse DNS entries to claim they’re Googlebot IP addresses. “This is something that is normally done only by quite bad actors,” Siebenmann warns.

The only archival service receiving Siebenmann’s approval is archive.org, which he describes as “a better behaved archival crawler” capable of accessing his content without triggering security measures.

This digital fortification represents a growing trend among content creators who find themselves caught between protecting their intellectual property and maintaining open access to their work. As AI training data becomes increasingly valuable, the battle between content creators and automated scrapers is intensifying, with ordinary internet users often finding themselves in the crossfire.

The move raises fundamental questions about the future of web accessibility and the balance between content protection and open information sharing in an era where AI systems are voraciously consuming digital content to fuel their learning algorithms.

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