PerplexityBot
Perplexity's answer-engine crawler. Allow it in robots.txt so Perplexity can index and cite your pages.
PerplexityBot fetches pages so Perplexity's answer engine can cite them with a source link. Perplexity leans heavily on live citations, so being fetchable is what earns the mention.
User-agent: PerplexityBot
Allow: /