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 · 268 ms

HostCertsFirst seenLast seenDNS
firstharrison.com 16 2026-05-05 2026-08-31 ok
*.firstharrison.com 16 2026-05-05 2026-08-31 —
cardwizard.firstharrison.com 1 2025-11-13 2025-11-13 nxdomain
secure.firstharrison.com 10 2026-05-23 2026-09-19 ok
train.firstharrison.com 15 2026-05-30 2026-09-25 ok
*.train.firstharrison.com 15 2026-05-30 2026-09-25 —
intranet.firstharrison.com 3 2026-05-27 2026-08-25 nodata
billpay.firstharrison.com 1 2026-02-23 2026-02-23 nxdomain
www.billpay.firstharrison.com 1 2026-02-23 2026-02-23 nxdomain

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