Find every subdomain
of a domain.

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

3 hosts · 245 ms

HostCertsFirst seenLast seen
cydea.com 4 2026-06-12 2026-10-10
support.cydea.com 5 2026-04-22 2026-08-20
www.cydea.com 4 2026-06-12 2026-10-10

Programmatic access: API GET /v1/hosts/cydea.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/cydea.com.