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.

6 hosts · 352 ms

HostCertsFirst seenLast seenDNS
redsift.co 12 2026-05-11 2026-09-06 ok
*.redsift.co 12 2026-05-11 2026-09-06 —
mx0.redsift.co 7 2026-04-28 2026-08-26 ok
mx1.redsift.co 7 2026-04-28 2026-08-26 ok
public.redsift.co 2 2025-07-23 2026-06-23 ok
mta-sts.redsift.co 2 2025-09-30 2026-08-31 ok

Programmatic access, with DNS A records: API GET /v1/hosts/redsift.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/redsift.co.