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.

5 hosts · 246 ms

HostCertsFirst seenLast seenDNS
bisg.edu.pl 5 2026-05-06 2026-09-27 ok
pl.bisg.edu.pl 5 2026-05-06 2026-09-27 ok
www.pl.bisg.edu.pl 5 2026-05-06 2026-09-27 ok
emails.bisg.edu.pl 5 2026-05-25 2026-09-22 ok
www.bisg.edu.pl 5 2026-05-05 2026-09-27 ok

Programmatic access, with DNS A records: API GET /v1/hosts/bisg.edu.pl (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/bisg.edu.pl.