Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts and first/last seen dates.

3 hosts · 211 ms

HostCertsFirst seenLast seen
sophos.at 2 2025-07-24 2026-06-23
mta-sts.sophos.at 5 2026-06-04 2026-10-05
www.sophos.at 2 2025-07-24 2026-06-23

Programmatic access: API GET /v1/hosts/sophos.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/sophos.at.