Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

6 hosts · 257 ms

HostCertsFirst seenLast seenDNS
ab-test.jp 2 2025-06-14 2026-06-15 ok
admin.ab-test.jp 1 2025-10-15 2025-10-15 ok
www.admin.ab-test.jp 1 2025-10-15 2025-10-15 nxdomain
mta-sts.ab-test.jp 5 2026-05-23 2026-09-20 ok
sys.ab-test.jp 1 2025-10-15 2025-10-15 ok
www.sys.ab-test.jp 1 2025-10-15 2025-10-15 nxdomain

Programmatic access, with DNS A records: API GET /v1/hosts/ab-test.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/ab-test.jp.