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.

2 hosts · 226 ms

HostCertsFirst seenLast seenDNS
s-asg.at 3 2025-10-16 2026-09-29 ok
www.s-asg.at 3 2025-10-16 2026-09-29 ok

Programmatic access, with DNS A records: API GET /v1/hosts/s-asg.at (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-asg.at.