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 · 280 ms

HostCertsFirst seenLast seenDNS
exr.education 3 2025-11-28 2026-01-18 ok
*.exr.education 2 2026-01-17 2026-01-18 —
www.exr.education 1 2025-11-28 2025-11-28 ok

Programmatic access, with DNS A records: API GET /v1/hosts/exr.education (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/exr.education.