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.

3 hosts · 263 ms

HostCertsFirst seenLast seenDNS
postnl.com 6 2026-05-13 2026-09-30 ok
mta-sts.postnl.com 5 2026-05-14 2026-10-04 ok
www.postnl.com 5 2026-06-08 2026-09-24 ok

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