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.

4 hosts · 234 ms

HostCertsFirst seenLast seen
amion.com 3 2025-08-05 2026-07-06
*.amion.com 3 2025-08-05 2026-07-06
support.amion.com 5 2026-04-30 2026-08-28
academy.amion.com 4 2026-04-19 2026-08-21

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