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.

6 hosts · 305 ms

HostCertsFirst seenLast seenDNS
cynethealth.com 24 2026-04-11 2026-10-06 ok
*.cynethealth.com 9 2026-05-07 2026-09-29 —
unsubscribe.cynethealth.com 5 2026-04-26 2026-08-25 ok
helpdesk.cynethealth.com 8 2026-05-13 2026-09-08 ok
jobs.cynethealth.com 3 2026-06-29 2026-08-28 ok
www.cynethealth.com 16 2026-04-11 2026-10-06 ok

Programmatic access, with DNS A records: API GET /v1/hosts/cynethealth.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/cynethealth.com.