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 · 200 ms

HostCertsFirst seenLast seenDNS
robertwalters.co.jp 2 2025-09-01 2026-08-19 ok
etime.robertwalters.co.jp 11 2026-04-15 2026-10-04 ok
ctp.robertwalters.co.jp 5 2026-05-29 2026-09-26 ok
mynumber.robertwalters.co.jp 10 2026-05-03 2026-10-04 ok
www.robertwalters.co.jp 2 2025-09-01 2026-08-19 ok

Programmatic access, with DNS A records: API GET /v1/hosts/robertwalters.co.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/robertwalters.co.jp.