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 · 243 ms

HostCertsFirst seenLast seenDNS
tascperformance.com 17 2026-04-20 2026-09-26 ok
*.tascperformance.com 6 2026-04-20 2026-08-17 —
mta-sts.tascperformance.com 4 2026-05-13 2026-10-03 ok
www.tascperformance.com 15 2026-05-15 2026-09-25 ok

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