Perplexity A.I. Is Lying About Its User Agent

Robb Knight blocked various web scrapers via robots.txt and through nginx. Yet Perplexity seemed to be able to access his site:

I got a perfect summary of the post including various details that they couldn’t have just guessed. Read the full response here. So what the fuck are they doing?


Before I got a chance to check my logs to see their user agent, Lewis had already done it. He got the following user agent string which certainly doesn’t include PerplexityBot like it should: […]

I am sure Perplexity will respond to this by claiming it was inadvertent, and it has fixed the problem, and it respects publishers’ choices to opt out of web scraping. What matters is how we have only a small amount of control over how our information is used on the web. It defaults to open and public — which is part of the web’s brilliance, until the audience is no longer human.

Unless we want to lock everything behind a login screen, the only mechanisms for control that we have are dependent on companies like Perplexity being honest about their bots. There is no chance this problem only affects the scraping of a handful of independent publishers; this is certainly widespread. Without penalty or legal reform, A.I. companies have little incentive not to do exactly the same as Perplexity.