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 · 368 ms

HostCertsFirst seenLast seenDNS
columbiagasohio.com 3 2026-03-18 2026-09-25 ok
cdrstage.columbiagasohio.com 2 2026-03-31 2026-08-26 ok
myaccount.columbiagasohio.com 3 2026-03-18 2026-09-25 ok
cdrstage-myaccount.columbiagasohio.com 2 2026-03-31 2026-08-26 ok
www.columbiagasohio.com 3 2026-03-18 2026-09-25 ok

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