Applebot

Applebot is Apple's internal which collects website data for its Siri and Spotlight services.

History
Logs of Applebot activity were first spotted in November 2014. Documentation about it began appearing in 2015. Applebot operates in a similar manner as from Google and can support Googlebot instructions if Applebot-specific instructions are not available.

Ranking criteria
Applebot uses the following criteria to rank its search results. The is not publicly available outside of its Siri and Spotlight services. End users are subject to Apple's privacy policy.
 * Aggregated user engagement with search results.
 * Relevancy and matching of search terms to webpage topics and content.
 * Number and quality of links from other pages on the web.
 * User location based signals (approximate data).
 * Webpage design characteristics.