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 · 250 ms

HostCertsFirst seenLast seenDNS
hsgroup.com 6 2026-02-18 2026-08-28 ok
*.hsgroup.com 4 2026-08-26 2026-08-28 —
hub.hsgroup.com 4 2026-05-10 2026-07-14 ok
mta-sts.hsgroup.com 2 2025-06-10 2026-05-11 ok
www.hsgroup.com 5 2026-02-23 2026-09-24 ok
*.www.hsgroup.com 3 2026-09-22 2026-09-24 —

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