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.

3 hosts · 245 ms

HostCertsFirst seenLast seenDNS
passivewriter.com 14 2026-04-12 2026-08-20 ok
*.passivewriter.com 11 2026-04-12 2026-08-05 —
parula.passivewriter.com 1 2026-04-15 2026-04-15 nxdomain

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