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 · 363 ms

HostCertsFirst seenLast seenDNS
emphasis.com 5 2025-10-09 2026-08-20 ok
*.emphasis.com 5 2025-10-09 2026-08-20 —

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