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.

7 hosts · 259 ms

HostCertsFirst seenLast seen
arto.com 3 2026-01-04 2026-09-04
rustic.arto.com 4 2026-04-21 2026-09-08
secure.arto.com 4 2026-05-04 2026-07-13
merchandising.arto.com 1 2026-08-16 2026-08-16
blog.arto.com 4 2026-04-20 2026-08-20
samplechips.arto.com 1 2026-08-16 2026-08-16
www.arto.com 5 2026-05-15 2026-09-04

Programmatic access: API GET /v1/hosts/arto.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/arto.com.