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.

5 hosts · 293 ms

HostCertsFirst seenLast seenDNS
caseteroid.com 22 2026-04-13 2026-09-26 ok
*.caseteroid.com 7 2026-05-18 2026-09-18 —
account.caseteroid.com 15 2026-04-13 2026-09-26 ok
support.caseteroid.com 6 2026-06-10 2026-08-08 ok
www.caseteroid.com 17 2026-04-13 2026-09-27 ok

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