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.

4 hosts · 405 ms

HostCertsFirst seenLast seenDNS
cloud.mail.travelhx.com 1 2026-01-08 2026-01-08 ok
image.mail.travelhx.com 3 2026-02-04 2026-02-16 ok
click.mail.travelhx.com 1 2026-01-08 2026-01-08 ok
view.mail.travelhx.com 1 2026-01-08 2026-01-08 ok

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