How Perplexity is Evading Anti-crawling Measures
Perplexity is using stealth, undeclared crawlers to evade website no-crawl directives2025-08-04Gabriel CorralVaibhav SinghalBrian MitchellReid Tatoris5 min readWe are observing stealth crawling behavior from Perplexity, an AI-powered answer engine. Although Perplexity initially crawls from their declared user agent, when they are presented with a network block, they appear to obscure their crawling identity in an attempt to circumvent the website’s preferences. We see continued evidence that Perplexity is repeatedly modifying their user agent and changing their source ASNs to hide their crawling activity, as well as ignoring — or sometimes failing to even fetch — robots.txt files.The Internet as we have known it for the past three decades is rapidly changing, but one thing remains…
