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 · 252 ms

HostCertsFirst seenLast seen
c4splus.com 12 2026-05-07 2026-10-07
*.c4splus.com 12 2026-05-07 2026-10-07
t-staging.c4splus.com 1 2026-07-20 2026-07-20
*.t-staging.c4splus.com 1 2026-07-20 2026-07-20
t.c4splus.com 1 2026-07-20 2026-07-20
*.t.c4splus.com 1 2026-07-20 2026-07-20

Programmatic access: API GET /v1/hosts/c4splus.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/c4splus.com.