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 · 177 ms

HostCertsFirst seenLast seen
a7.co 12 2026-05-16 2026-09-26
returns.a7.co 8 2026-05-15 2026-09-10
account.a7.co 15 2026-04-18 2026-10-02
www.a7.co 10 2026-05-16 2026-09-24

Programmatic access: API GET /v1/hosts/a7.co (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/a7.co.