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.

7 hosts · 331 ms

HostCertsFirst seenLast seen
procern.com 24 2026-01-30 2026-10-02
*.procern.com 18 2026-05-18 2026-10-02
staging2.procern.com 3 2026-07-13 2026-09-11
update.procern.com 18 2026-05-18 2026-09-13
bimi.procern.com 6 2026-05-25 2026-09-20
linksmtp2go.procern.com 7 2026-05-08 2026-09-05
www.procern.com 5 2026-06-01 2026-09-29

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