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 · 285 ms

HostCertsFirst seenLast seenDNS
itgeeks.com 24 2025-08-03 2026-08-17 ok
*.itgeeks.com 2 2025-08-03 2026-08-04 —
newsletter.itgeeks.com 2 2026-09-25 2026-09-25 ok
elink520.newsletter.itgeeks.com 2 2026-09-25 2026-09-25 ok
www.itgeeks.com 22 2026-04-12 2026-08-10 ok

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