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 · 346 ms

HostCertsFirst seenLast seenDNS
www.mydocomo.com 6 2025-09-03 2026-09-09 ok
apibiz.mydocomo.com 2 2025-07-28 2026-06-28 ok
m2.apibiz.mydocomo.com 4 2025-06-26 2026-08-20 nxdomain
dev.apibiz.mydocomo.com 2 2025-06-26 2026-05-27 ok

Programmatic access, with DNS A records: API GET /v1/hosts/mydocomo.com (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/mydocomo.com.