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 · 263 ms

HostCertsFirst seenLast seen
alanhealth.co 22 2026-05-12 2026-09-30
*.alanhealth.co 10 2026-06-03 2026-09-30
www.alanhealth.co 8 2026-05-12 2026-09-07

Programmatic access: API GET /v1/hosts/alanhealth.co (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/alanhealth.co.