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.

6 hosts · 333 ms

HostCertsFirst seenLast seenDNS
nightfallgroup.com 17 2026-05-14 2026-09-26 ok
*.nightfallgroup.com 17 2026-05-14 2026-09-26 —
send.nightfallgroup.com 16 2026-05-25 2026-09-21 ok
tracking.nightfallgroup.com 17 2026-05-12 2026-09-30 ok
cdn.nightfallgroup.com 10 2026-05-24 2026-09-19 ok
pms.nightfallgroup.com 5 2026-05-17 2026-09-16 ok

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