Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

2 hosts · 214 ms

HostCertsFirst seenLast seenDNS
saitama-kenkou.or.jp 1 2026-06-19 2026-06-19 ok
www.saitama-kenkou.or.jp 1 2026-06-19 2026-06-19 ok

Programmatic access, with DNS A records: API GET /v1/hosts/saitama-kenkou.or.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/saitama-kenkou.or.jp.