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.

4 hosts · 271 ms

HostCertsFirst seenLast seenDNS
wa.edu 4 2026-06-03 2026-10-03 ok
thenextchapter.wa.edu 5 2026-05-18 2026-09-17 ok
www.thenextchapter.wa.edu 5 2026-05-18 2026-09-17 ok
www.wa.edu 4 2026-06-03 2026-10-03 ok

Programmatic access, with DNS A records: API GET /v1/hosts/wa.edu (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/wa.edu.