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.

4 hosts · 303 ms

HostCertsFirst seenLast seenDNS
greystoneprograms.org 4 2026-05-27 2026-08-05 ok
en.greystoneprograms.org 4 2026-04-17 2026-09-03 ok
mta-sts.greystoneprograms.org 1 2026-06-30 2026-06-30 nodata
www.greystoneprograms.org 4 2026-05-27 2026-08-05 ok

Programmatic access, with DNS A records: API GET /v1/hosts/greystoneprograms.org (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/greystoneprograms.org.