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.

7 hosts · 220 ms

HostCertsFirst seenLast seenDNS
ksk-koeln.de 4 2026-03-31 2026-09-18 ok
psd2-xs2a.ksk-koeln.de 3 2025-09-08 2026-08-14 nxdomain
service.ksk-koeln.de 5 2026-05-06 2026-09-03 ok
teamfinance.ksk-koeln.de 3 2026-04-15 2026-06-14 ok
module.ksk-koeln.de 4 2026-03-31 2026-09-18 ok
psd2-xs2a.portal.ksk-koeln.de 1 2026-05-26 2026-05-26 nxdomain
www.ksk-koeln.de 4 2026-03-31 2026-09-18 ok

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