http://magma.ua4vjlx72wv5crhkificaeysp62hizhazipfshsdvs6jxqvhtkpllcad.onion/guide/osint-sources.html
Censys - Get Censys data for a domain name such
as open ports, DNS configuration, TLS certificate information. FortiGuard Labs - FortiGuard Labs OSINT domain
report. MX Toolbox - MX
statistics, IP/host reputation, DNS, blacklist and SMTP diagnostics.