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.

9 hosts · 167 ms

HostCertsFirst seenLast seen
res2.email.assu2000.com 1 2025-11-12 2025-11-12
t2.email.assu2000.com 2 2025-11-12 2025-11-12
m3.email.assu2000.com 2 2025-11-12 2025-11-12
res3.email.assu2000.com 1 2025-11-12 2025-11-12
t3.email.assu2000.com 2 2025-11-12 2025-11-12
web.email.assu2000.com 2 2025-11-12 2025-11-12
m.email.assu2000.com 2 2025-11-12 2025-11-12
res.email.assu2000.com 4 2025-11-12 2026-10-04
t.email.assu2000.com 2 2025-11-12 2025-11-12

Programmatic access: API GET /v1/hosts/assu2000.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/assu2000.com.