Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts and first/last seen dates.

4 hosts · 252 ms

HostCertsFirst seenLast seen
rakuten.us 4 2026-02-19 2026-10-03
optimism.rakuten.us 8 2026-04-17 2026-09-27
member.insight.rakuten.us 3 2026-04-02 2026-09-04
www.rakuten.us 4 2026-02-20 2026-10-05

Programmatic access: API GET /v1/hosts/rakuten.us (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/rakuten.us.