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.

2 hosts · 221 ms

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HostCertsFirst seenLast seen
s-square.net 2 2026-05-11 2026-10-06
www.s-square.net 3 2026-05-12 2026-10-07

Programmatic access: API GET /v1/hosts/s-square.net (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-square.net.