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.

4 hosts · 357 ms

HostCertsFirst seenLast seenDNS
eventsource.ca 35 2026-04-09 2026-09-18 ok
*.eventsource.ca 32 2026-04-09 2026-09-18 —
growth.eventsource.ca 5 2026-06-01 2026-09-29 ok
t.eventsource.ca 5 2026-04-30 2026-08-28 ok

Programmatic access, with DNS A records: API GET /v1/hosts/eventsource.ca (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/eventsource.ca.