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.

11 hosts · 251 ms

HostCertsFirst seenLast seen
sixapart.jp 6 2025-12-17 2026-08-21
*.sixapart.jp 2 2025-12-17 2026-02-16
tophhana.sixapart.jp 5 2026-04-29 2026-08-28
blog.sixapart.jp 5 2026-04-22 2026-08-21
intrablog.sixapart.jp 1 2026-05-24 2026-05-24
mtuser.sixapart.jp 2 2025-07-30 2026-08-26
newsletter.sixapart.jp 5 2026-06-07 2026-10-07
tpks.sixapart.jp 4 2026-06-10 2026-10-09
intranet.sixapart.jp 1 2025-10-27 2025-10-27
pronet.sixapart.jp 4 2026-04-19 2026-08-15
www.sixapart.jp 5 2026-04-22 2026-08-21

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