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.

3 hosts · 295 ms

HostCertsFirst seenLast seenDNS
gaacc.com 5 2026-05-23 2026-09-05 ok
mta-sts.gaacc.com 9 2026-05-16 2026-09-13 ok
www.gaacc.com 5 2026-05-19 2026-09-06 ok

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