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.

6 hosts · 253 ms

HostCertsFirst seenLast seen
youi.email 2 2025-07-07 2026-06-29
mail.youi.email 2 2025-07-07 2026-06-29
autodiscover.youi.email 2 2025-07-07 2026-06-29
ablinks.youi.email 1 2026-06-18 2026-06-18
www.ablinks.youi.email 1 2026-06-18 2026-06-18
www.youi.email 2 2025-07-07 2026-06-29

Programmatic access: API GET /v1/hosts/youi.email (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/youi.email.