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.

2 hosts · 229 ms

HostCertsFirst seenLast seenDNS
b2-online.jp 2 2026-01-14 2026-01-27 ok
*.b2-online.jp 3 2025-12-11 2026-01-28 —

Programmatic access, with DNS A records: API GET /v1/hosts/b2-online.jp (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/b2-online.jp.