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 · 233 ms

HostCertsFirst seenLast seenDNS
fastenersplus.com 14 2026-05-20 2026-09-28 ok
tracking.fastenersplus.com 14 2026-05-25 2026-09-20 ok
trk.fastenersplus.com 9 2026-06-04 2026-10-01 ok
account.fastenersplus.com 9 2026-04-20 2026-08-29 ok
www.fastenersplus.com 14 2026-05-19 2026-09-30 ok

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