Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

4 hosts · 243 ms

HostCertsFirst seenLast seenDNS
hcsclean.com 18 2026-05-18 2026-09-18 ok
*.hcsclean.com 9 2026-05-18 2026-09-13 —
mta-sts.hcsclean.com 9 2026-05-22 2026-09-18 ok
*.mta-sts.hcsclean.com 9 2026-05-22 2026-09-18 —

Programmatic access, with DNS A records: API GET /v1/hosts/hcsclean.com (API key for paging).

Shown here: hostnames with a certificate that is valid now or expired within the last 90 days. The full history since 2013 — hostnames whose last certificate expired earlier — is a Pro plan method: GET /v1/hosts-history/hcsclean.com.