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.

3 hosts · 257 ms

HostCertsFirst seenLast seenDNS
sslexpiry.com 15 2026-04-23 2026-10-05 ok
cdn.sslexpiry.com 9 2026-04-17 2026-09-29 servfail
www.sslexpiry.com 15 2026-04-23 2026-10-05 ok

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