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.

7 hosts · 232 ms

HostCertsFirst seenLast seenDNS
koukoku.jp 17 2026-05-02 2026-08-28 ok
*.koukoku.jp 16 2026-05-02 2026-08-28 —
ai-lab.koukoku.jp 6 2026-05-30 2026-09-29 ok
stg-ai-lab.koukoku.jp 3 2026-06-16 2026-08-16 ok
sgtm.koukoku.jp 4 2026-04-09 2026-09-15 ok
shop.koukoku.jp 1 2026-09-30 2026-09-30 nodata
www.koukoku.jp 1 2026-06-12 2026-06-12 ok

Programmatic access, with DNS A records: API GET /v1/hosts/koukoku.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/koukoku.jp.