PerplexityBot is the search crawler of Perplexity, an AI assistant that gives answers with source links. Perplexity’s crawler documentation states that the bot is meant to show and link websites in Perplexity’s search results. Perplexity advises sites that want to appear there to allow PerplexityBot in robots.txt. The user agent looks like this:
Mozilla/5.0 (compatible; PerplexityBot/1.0; +https://perplexity.ai/perplexitybot)Perplexity-User
Besides PerplexityBot, Perplexity has a fetcher called Perplexity-User. It visits a page when a user asks a question, so the answer can link to the source. Because a user makes the request, Perplexity-User generally ignores robots.txt, according to Perplexity. The documentation also states that Perplexity-User is not used for training.
Example
User-agent: PerplexityBot
Allow: /Common mistake
Thinking that a rule for PerplexityBot controls every visit from Perplexity. Visits by Perplexity-User are usually not covered by it. If you really want to shield a page, put it behind a password or login.
More in Allowing or blocking AI crawlers with robots.txt and under AI crawler.