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.

3 hosts · 356 ms

HostCertsFirst seenLast seen
atheon.co.uk 2 2025-06-29 2026-05-30
mta-sts.atheon.co.uk 2 2025-07-14 2026-06-14
www.atheon.co.uk 5 2026-05-31 2026-09-13

Programmatic access: API GET /v1/hosts/atheon.co.uk (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/atheon.co.uk.