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.

10 hosts · 311 ms

HostCertsFirst seenLast seenDNS
thehealthy.com 8 2026-05-24 2026-09-19 ok
*.thehealthy.com 7 2026-05-24 2026-09-19 —
sli.thehealthy.com 2 2025-06-28 2026-05-29 ok
ca.mail.thehealthy.com 4 2026-04-12 2026-08-10 ok
e.mail.thehealthy.com 4 2026-04-12 2026-08-10 ok
images.mail.thehealthy.com 2 2025-08-01 2026-07-02 ok
view.mail.thehealthy.com 2 2025-08-01 2026-07-02 ok
tachyon.thehealthy.com 3 2026-05-15 2026-08-30 ok
bytes.thehealthy.com 3 2026-05-26 2026-08-04 ok
tollbit.thehealthy.com 26 2026-04-07 2026-09-18 ok

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