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 · 275 ms

HostCertsFirst seenLast seenDNS
dub.co 10 2026-04-23 2026-08-26 ok
*.dub.co 5 2026-04-23 2026-08-26 —
rs.mail.dub.co 3 2026-05-01 2026-10-01 ok
rs.ship.dub.co 2 2026-05-01 2026-10-01 ok
app.dub.co 2 2026-04-23 2026-04-23 ok
rs.dub.co 2 2026-05-01 2026-10-01 ok
assets.dub.co 2 2026-02-28 2026-07-16 ok

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