Free tools
No account needed. Each tool explains what it does, how to read the result, and what usually goes wrong.
WHOIS / RDAP lookup/tools/whoisWho registered a domain, when it expires, which registrar holds it, and which nameservers it uses.DNS lookup/tools/dns-lookupA, AAAA, CNAME, MX, TXT and NS records for any hostname, including the underscore names that carry DKIM and DMARC.SSL certificate checker/tools/ssl-checkerIssuer, expiry date, covered names, and whether the certificate chain is complete.Domain name generator/tools/name-generatorKeyword to suggestions across endings, each checked for availability.Bulk availability checker/tools/bulk-checkPaste a list of names and check them all at once.