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 · 363 ms

HostCertsFirst seenLast seenDNS
workwithyoung.com 10 2026-04-22 2026-08-18 ok
www.workwithyoung.com 10 2026-04-23 2026-08-19 ok
pay.workwithyoung.com 1 2026-06-02 2026-06-02 ok
www.pay.workwithyoung.com 1 2026-06-02 2026-06-02 nxdomain

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