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.

2 hosts · 308 ms

HostCertsFirst seenLast seenDNS
rhii.com 2 2025-08-12 2026-07-12 ok
*.rhii.com 4 2025-08-12 2026-09-06 —

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