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
bookhocking.com 12 2026-05-10 2026-09-17 ok
*.bookhocking.com 7 2026-05-17 2026-09-17 —
www.bookhocking.com 5 2026-05-10 2026-09-08 ok

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