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.

4 hosts · 254 ms

HostCertsFirst seenLast seen
geeksupport.com 14 2026-05-28 2026-09-23
go.geeksupport.com 16 2026-05-11 2026-09-06
support.geeksupport.com 5 2026-05-12 2026-09-09
www.geeksupport.com 20 2026-05-28 2026-09-23

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