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.

3 hosts · 265 ms

HostCertsFirst seenLast seenDNS
brainstation.io 16 2025-10-15 2026-09-25 ok
*.brainstation.io 16 2025-10-15 2026-09-25 —
international.brainstation.io 12 2026-04-30 2026-08-26 ok

Programmatic access, with DNS A records: API GET /v1/hosts/brainstation.io (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/brainstation.io.