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.

7 hosts · 302 ms

HostCertsFirst seenLast seenDNS
tsubakimoto.com 2 2025-10-13 2026-01-22 ok
twins.tsubakimoto.com 4 2026-05-05 2026-07-04 ok
www.twins.tsubakimoto.com 4 2026-05-05 2026-07-04 ok
mta-sts.tsubakimoto.com 5 2026-05-05 2026-09-02 ok
contact.tsubakimoto.com 5 2026-05-19 2026-09-16 ok
mt.tsubakimoto.com 5 2026-05-02 2026-08-30 ok
www.tsubakimoto.com 2 2025-10-13 2026-01-22 ok

Programmatic access, with DNS A records: API GET /v1/hosts/tsubakimoto.com (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/tsubakimoto.com.