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.

4 hosts · 263 ms

HostCertsFirst seenLast seenDNS
tsubaki.co.uk 4 2025-07-23 2026-08-14 ok
mta-sts.tsubaki.co.uk 5 2026-05-05 2026-09-02 ok
www.mta-sts.tsubaki.co.uk 5 2026-05-05 2026-09-02 ok
www.tsubaki.co.uk 4 2025-07-23 2026-08-14 ok

Programmatic access, with DNS A records: API GET /v1/hosts/tsubaki.co.uk (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/tsubaki.co.uk.