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.

5 hosts · 287 ms

HostCertsFirst seenLast seenDNS
willowtongroup.com 24 2025-10-02 2026-10-06 ok
*.willowtongroup.com 3 2025-10-02 2026-09-29 —
sup.willowtongroup.com 4 2026-04-15 2026-08-15 ok
mta-sts.willowtongroup.com 3 2026-05-26 2026-08-20 ok
www.willowtongroup.com 15 2026-06-06 2026-10-05 ok

Programmatic access, with DNS A records: API GET /v1/hosts/willowtongroup.com (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/willowtongroup.com.