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 · 260 ms

HostCertsFirst seenLast seen
koto.com 13 2026-05-16 2026-10-03
*.koto.com 8 2026-05-18 2026-10-03
atlas.koto.com 5 2026-04-23 2026-08-25

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