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.

5 hosts · 227 ms

HostCertsFirst seenLast seenDNS
opera.fi 15 2025-08-19 2026-08-31 ok
*.opera.fi 9 2025-08-19 2026-08-31 —
diese-reports.opera.fi 4 2026-04-20 2026-08-23 ok
intranet.opera.fi 5 2026-05-20 2026-08-19 ok
www.opera.fi 5 2026-05-20 2026-08-19 ok

Programmatic access, with DNS A records: API GET /v1/hosts/opera.fi (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/opera.fi.