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.

13 hosts · 229 ms

HostCertsFirst seenLast seenDNS
guestplan.com 18 2026-04-16 2026-10-04 ok
*.guestplan.com 13 2026-04-16 2026-10-04 —
appcf.guestplan.com 10 2026-05-01 2026-08-28 ok
cdn-img.guestplan.com 10 2026-05-16 2026-09-11 ok
dish.guestplan.com 2 2026-09-13 2026-09-13 ok
api.guestplan.com 1 2025-11-27 2025-11-27 ok
cdn.guestplan.com 12 2026-04-30 2026-08-27 ok
help.guestplan.com 5 2026-04-21 2026-08-20 ok
app.guestplan.com 10 2026-04-24 2026-08-20 ok
docs.guestplan.com 5 2026-04-21 2026-08-20 ok
widget.guestplan.com 10 2026-04-30 2026-08-27 ok
cdn-att.guestplan.com 11 2026-05-19 2026-09-15 ok
www.guestplan.com 5 2026-05-26 2026-09-24 ok

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