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 · 222 ms

HostCertsFirst seenLast seenDNS
cloud.rt.ssfcu.org 2 2025-12-24 2026-01-05 ok
image.rt.ssfcu.org 3 2026-01-12 2026-02-02 ok
click.rt.ssfcu.org 1 2026-01-14 2026-01-14 ok
view.rt.ssfcu.org 1 2026-01-14 2026-01-14 ok

Programmatic access, with DNS A records: API GET /v1/hosts/rt.ssfcu.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/rt.ssfcu.org.