Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts and first/last seen dates.

7 hosts · 263 ms

HostCertsFirst seenLast seen
helpareporter.com 4 2026-04-17 2026-08-20
blog.helpareporter.com 14 2026-05-30 2026-09-25
www.blog.helpareporter.com 16 2026-05-31 2026-09-26
clerk.helpareporter.com 8 2026-05-14 2026-09-09
accounts.helpareporter.com 8 2026-05-13 2026-09-09
dev.helpareporter.com 4 2026-04-20 2026-08-21
www.helpareporter.com 3 2026-06-11 2026-08-11

Programmatic access: API GET /v1/hosts/helpareporter.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/helpareporter.com.