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 · 258 ms

HostCertsFirst seenLast seenDNS
ec.nicos.co.jp 2 2026-02-18 2026-02-18 ok
b2b.ec.nicos.co.jp 1 2026-02-18 2026-02-18 ok
st.ec.nicos.co.jp 2 2026-01-13 2026-01-13 ok
b2bst.ec.nicos.co.jp 1 2026-01-13 2026-01-13 ok
test.ec.nicos.co.jp 1 2026-01-13 2026-01-13 ok
b2b.test.ec.nicos.co.jp 1 2026-01-13 2026-01-13 ok

Programmatic access, with DNS A records: API GET /v1/hosts/ec.nicos.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/ec.nicos.co.jp.