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.

4 hosts · 217 ms

HostCertsFirst seenLast seen
sophos.nl 3 2025-09-30 2026-08-30
*.sophos.nl 2 2025-09-30 2026-08-30
mta-sts.sophos.nl 6 2026-06-03 2026-10-01
www.sophos.nl 1 2026-01-24 2026-01-24

Programmatic access: API GET /v1/hosts/sophos.nl (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.nl.