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.

5 hosts · 335 ms

HostCertsFirst seenLast seenDNS
s-os.de 2 2025-12-22 2026-08-25 ok
psd2-xs2a.s-os.de 1 2026-06-01 2026-06-01 nxdomain
module.s-os.de 3 2026-01-08 2026-08-25 ok
mailing.s-os.de 1 2026-08-13 2026-08-13 ok
www.s-os.de 3 2026-01-08 2026-08-25 ok

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