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.

3 hosts · 221 ms

HostCertsFirst seenLast seen
gcpauth.hfhd.co.jp 3 2026-05-13 2026-08-28
www.hfhd.co.jp 125 2025-06-30 2026-09-28
entry.hfhd.co.jp 125 2025-06-30 2026-09-28

Programmatic access: API GET /v1/hosts/hfhd.co.jp (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/hfhd.co.jp.