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 · 202 ms

HostCertsFirst seenLast seen
machineseeker.biz 5 2026-05-23 2026-09-21
www.machineseeker.biz 5 2026-05-23 2026-09-21

Programmatic access: API GET /v1/hosts/machineseeker.biz (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/machineseeker.biz.