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 · 231 ms

HostCertsFirst seenLast seenDNS
spelldata.co.jp 29 2026-05-08 2026-09-30 ok
*.spelldata.co.jp 29 2026-05-08 2026-09-30 —
mta-sts.spelldata.co.jp 3 2026-05-31 2026-08-10 ok
connect.spelldata.co.jp 12 2026-05-07 2026-09-05 ok
support.spelldata.co.jp 10 2026-05-05 2026-09-03 ok

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