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 · 166 ms

HostCertsFirst seenLast seen
cloud.email3.humana.com 2 2025-07-15 2026-07-02
image.email3.humana.com 4 2025-06-11 2026-09-07
click.email3.humana.com 2 2025-07-15 2026-07-03
view.email3.humana.com 2 2025-07-17 2026-07-06

Programmatic access: API GET /v1/hosts/email3.humana.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/email3.humana.com.