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.

9 hosts · 337 ms

HostCertsFirst seenLast seenDNS
tricount.com 1 2026-01-14 2026-01-14 ok
*.tricount.com 1 2026-01-14 2026-01-14 —
help.triage.tricount.com 3 2025-08-26 2026-07-27 ok
track.update.tricount.com 4 2026-04-18 2026-08-16 ok
www.blog.tricount.com 1 2026-01-14 2026-01-14 ok
ideal.tricount.com 4 2025-10-07 2026-09-07 ok
track.hello.tricount.com 4 2026-04-18 2026-08-16 ok
help.tricount.com 27 2026-04-23 2026-08-21 ok
clicks.tricount.com 2 2025-07-28 2026-06-28 ok

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