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 · 249 ms

HostCertsFirst seenLast seenDNS
cloud.info.doctors.columbia.edu 2 2025-11-05 2026-02-26 ok
image.info.doctors.columbia.edu 3 2026-02-12 2026-09-07 ok
click.info.doctors.columbia.edu 2 2025-11-05 2026-02-26 ok
view.info.doctors.columbia.edu 2 2025-11-05 2026-02-26 ok

Programmatic access, with DNS A records: API GET /v1/hosts/info.doctors.columbia.edu (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/info.doctors.columbia.edu.