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 · 281 ms

HostCertsFirst seenLast seenDNS
buoyantcap.com 7 2026-01-30 2026-09-11 ok
*.buoyantcap.com 7 2026-01-30 2026-09-11 —
fa.buoyantcap.com 7 2026-04-28 2026-08-26 ok
img.campaign.buoyantcap.com 6 2026-04-14 2026-08-11 ok
r.campaign.buoyantcap.com 3 2026-06-17 2026-09-05 ok

Programmatic access, with DNS A records: API GET /v1/hosts/buoyantcap.com (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/buoyantcap.com.