Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts and first/last seen dates.

4 hosts · 262 ms

HostCertsFirst seenLast seen
hex.ai 14 2026-04-19 2026-10-08
*.hex.ai 14 2026-04-19 2026-10-08
hello.hex.ai 5 2026-05-08 2026-08-18
mta-sts.hex.ai 5 2026-05-02 2026-08-30

Programmatic access: API GET /v1/hosts/hex.ai (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/hex.ai.