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 · 242 ms

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HostCertsFirst seenLast seen
aalto.com 4 2026-06-11 2026-10-12
www.aalto.com 3 2026-06-16 2026-08-17

Programmatic access: API GET /v1/hosts/aalto.com (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/aalto.com.