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.

5 hosts · 344 ms

HostCertsFirst seenLast seenDNS
mtacd.org 1 2026-01-12 2026-01-12 nodata
*.mtacd.org 1 2026-01-12 2026-01-12 —
pif-stage.mtacd.org 5 2026-05-21 2026-09-18 ok
pif.mtacd.org 5 2026-05-23 2026-09-20 ok
autodiscover.mtacd.org 1 2025-08-12 2025-08-12 ok

Programmatic access, with DNS A records: API GET /v1/hosts/mtacd.org (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/mtacd.org.