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.

2 hosts · 216 ms

HostCertsFirst seenLast seen
reader.macsales.com 4 2025-10-08 2026-07-10
trk.send.reader.macsales.com 8 2026-05-02 2026-08-28

Programmatic access: API GET /v1/hosts/reader.macsales.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/reader.macsales.com.