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.

4 hosts · 249 ms

HostCertsFirst seenLast seenDNS
pc-koubou.jp 11 2026-05-28 2026-10-02 ok
*.pc-koubou.jp 11 2026-05-28 2026-10-02 —
dlmj.pc-koubou.jp 3 2026-05-24 2026-08-23 ok
www.pc-koubou.jp 1 2025-12-19 2025-12-19 ok

Programmatic access, with DNS A records: API GET /v1/hosts/pc-koubou.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/pc-koubou.jp.