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 · 261 ms

HostCertsFirst seenLast seenDNS
giac.org 19 2026-01-22 2026-10-01 ok
*.giac.org 19 2026-01-22 2026-10-01 —
go.giac.org 2 2025-08-01 2026-07-02 ok

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