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 · 283 ms

HostCertsFirst seenLast seen
hydratebuddy.co.uk 16 2026-04-17 2026-09-29
account.hydratebuddy.co.uk 13 2026-04-28 2026-09-05
www.hydratebuddy.co.uk 16 2026-04-15 2026-09-29

Programmatic access: API GET /v1/hosts/hydratebuddy.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/hydratebuddy.co.uk.