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.

2 hosts · 159 ms

HostCertsFirst seenLast seen
securemail.spglobal.com 3 2025-09-09 2026-08-19
www.securemail.spglobal.com 3 2025-09-09 2026-08-19

Programmatic access: API GET /v1/hosts/securemail.spglobal.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/securemail.spglobal.com.