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.

10 hosts · 318 ms

HostCertsFirst seenLast seenDNS
tychron.com 49 2026-04-19 2026-09-17 ok
*.tychron.com 28 2026-05-05 2026-09-17 —
compliance.tychron.com 18 2026-05-02 2026-08-29 ok
link.tychron.com 4 2026-04-10 2026-08-08 ok
helpdesk.tychron.com 10 2026-05-22 2026-09-19 ok
docs.tychron.com 13 2026-07-29 2026-09-29 ok
forms.tychron.com 22 2026-08-18 2026-10-02 ok
status.tychron.com 10 2026-05-07 2026-09-05 ok
chat.tychron.com 10 2026-05-15 2026-09-12 ok
www.tychron.com 22 2026-04-19 2026-10-02 ok

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