DomainTools Whoiswhois.domaintools.com
Free WHOIS lookup with hosting history and reverse IP hints. The paid Iris platform adds historical WHOIS, reverse WHOIS and infrastructure pivoting.
domainip / asndetails
tools / rdap-org
rdap.org
RDAP bootstrap redirector that sends a query for any domain, IP or ASN to the authoritative registry's RDAP server and returns structured JSON.
freeossapi
field note
Script it: curl https://rdap.org/domain/example.com or https://rdap.org/ip/1.1.1.1. JSON is much easier to parse than raw WHOIS text.
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