Ahrefs

Ahrefs is the leading SaaS-based SEO tool for keyword research, backlink analysis and monitoring competitors. Ahrefs spider constantly crawl the internet for updates and is currently aware of 5 billion web pages, 16 trillion links, 170 milion root domains and 3 trillion known URLs. All this data is hosted on 48 petabyte of storage and powered by 65,000 CPU cores.