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 · 231 ms

HostCertsFirst seenLast seenDNS
kasesul.jp 2 2026-02-20 2026-07-08 ok
*.kasesul.jp 2 2026-02-20 2026-07-08 —

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