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 · 246 ms

HostCertsFirst seenLast seen
xserver.co.jp 4 2026-04-08 2026-09-23
corporate.xserver.co.jp 5 2026-05-22 2026-09-19
www.xserver.co.jp 4 2026-04-08 2026-09-23

Programmatic access: API GET /v1/hosts/xserver.co.jp (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/xserver.co.jp.