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 · 237 ms

HostCertsFirst seenLast seen
citizenx.com 22 2026-04-18 2026-09-29
*.citizenx.com 18 2026-05-09 2026-09-29
media.citizenx.com 4 2026-04-18 2026-08-16
app.citizenx.com 1 2026-08-14 2026-08-14
cms.citizenx.com 1 2026-08-14 2026-08-14
insights.citizenx.com 5 2026-06-20 2026-09-08
asset.citizenx.com 10 2026-06-11 2026-10-07
www.citizenx.com 4 2026-04-18 2026-08-16
apply.citizenx.com 8 2026-06-07 2026-08-06

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