Website Informer
Website.informer: complete data lookup & free aggregated report on any domain including whois, visitors, IP & DNS details, competitors, owners, etc
Whois hosting this
WhoIsHostingThis identifies the web hosting provider for any domain, returning server location, nameserver data, and registrar information.
Whoisology
Whoisology is a cross-referenced database of current and historic domain ownership records for InfoSec, legal, and research professionals.
Whoxy
Whoxy provides a WHOIS lookup API with reverse WHOIS search and historical domain registration data for infrastructure investigation.
theHarvester
theHarvester collects emails, subdomains, IPs, and employee names from search engines and DNS records for passive OSINT reconnaissance.