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 · 223 ms

HostCertsFirst seenLast seenDNS
img.info4.supersmart.com 16 2026-05-11 2026-09-06 nxdomain
r.info4.supersmart.com 4 2026-04-11 2026-09-18 nxdomain

Programmatic access, with DNS A records: API GET /v1/hosts/info4.supersmart.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/info4.supersmart.com.