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.

5 hosts · 247 ms

HostCertsFirst seenLast seenDNS
medical-reserve.co.jp 10 2026-05-07 2026-09-07 ok
mx.system.medical-reserve.co.jp 5 2026-05-19 2026-09-22 ok
preview-recruit.medical-reserve.co.jp 4 2026-04-07 2026-08-11 ok
preview.medical-reserve.co.jp 4 2026-04-07 2026-08-11 ok
www.medical-reserve.co.jp 2 2026-09-06 2026-09-07 ok

Programmatic access, with DNS A records: API GET /v1/hosts/medical-reserve.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/medical-reserve.co.jp.