Domain, DNS & WHOIS
Investigate domains, DNS records, certificates and registration history.
DNSDumpster
Free domain research tool that maps a domain's subdomains and hosts.
Free
SecurityTrails
Historical DNS, WHOIS and subdomain data for domains and IP addresses.
Freemium
ViewDNS.info
Collection of free DNS, WHOIS, reverse-IP and network lookup tools.
Free
Whoxy
WHOIS lookup and reverse-WHOIS history, including registrant-name search.
Freemium
crt.sh
Searches Certificate Transparency logs to enumerate a domain's certificates and subdomains.
Free