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.

6 hosts · 227 ms

HostCertsFirst seenLast seenDNS
ksk-steinfurt.de 4 2026-04-14 2026-09-30 ok
psd2-xs2a.ksk-steinfurt.de 2 2025-08-11 2026-06-29 nxdomain
module.ksk-steinfurt.de 4 2026-04-14 2026-09-30 ok
mailing.ksk-steinfurt.de 4 2026-04-16 2026-08-14 ok
newsletter.ksk-steinfurt.de 5 2026-05-15 2026-09-12 ok
www.ksk-steinfurt.de 4 2026-04-14 2026-09-30 ok

Programmatic access, with DNS A records: API GET /v1/hosts/ksk-steinfurt.de (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/ksk-steinfurt.de.