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 · 268 ms

HostCertsFirst seenLast seenDNS
mcuholdings.com 12 2026-05-21 2026-09-16 ok
portal.mcuholdings.com 5 2026-05-12 2026-08-30 ok
www.mcuholdings.com 8 2026-05-25 2026-09-20 ok

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