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.

9 hosts · 305 ms

HostCertsFirst seenLast seenDNS
crossco.com 9 2025-12-21 2026-08-11 ok
*.crossco.com 9 2025-12-21 2026-08-11 —
msi.crossco.com 2 2026-09-23 2026-09-23 ok
helpdesk.crossco.com 8 2026-06-09 2026-10-07 ok
fusion.crossco.com 2 2026-09-23 2026-09-23 ok
crossnet.crossco.com 15 2026-04-20 2026-09-23 ok
my.crossco.com 5 2026-04-25 2026-09-04 ok
sbx1.my.crossco.com 5 2026-04-24 2026-09-03 ok
sbx2.my.crossco.com 5 2026-05-04 2026-09-13 ok

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