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.

8 hosts · 196 ms

HostCertsFirst seenLast seen
linestep.jp 5 2026-05-23 2026-09-20
test1.linestep.jp 4 2026-07-21 2026-09-19
stg.linestep.jp 5 2026-05-07 2026-09-04
cs.linestep.jp 2 2026-07-21 2026-07-21
contents.linestep.jp 9 2026-05-23 2026-09-18
qabot.linestep.jp 10 2026-05-04 2026-09-07
l-cast.linestep.jp 5 2026-05-03 2026-08-31
www.linestep.jp 5 2026-05-23 2026-09-20

Programmatic access: API GET /v1/hosts/linestep.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/linestep.jp.