Port Check
Is a TCP port reachable from the outside? Tells closed apart from filtered.
Enter a target
Enter a hostname or IP and pick a port to check whether it answers from outside.
Other tools
DNS LookupA, AAAA, CNAME, MX, TXT, NS, SOA and CAA records with their TTL values. DNS PropagationCompare what different resolvers answer for the same record. Mail RecordsMX, SPF, DKIM and DMARC in one view, with the mistakes that silently lose mail. WHOISRegistrar, creation and expiry dates, status codes and nameservers. SSL CertificateValidity, hostname match, issuer and chain, read straight from the handshake. HTTP HeadersStatus code, redirect chain, response time and security headers. Blacklist CheckIs the IP listed on the major DNSBL zones mail servers consult? Reverse DNSPTR record, forward-confirmed check and the network the address belongs to.