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.

6 hosts · 212 ms

HostCertsFirst seenLast seen
membrain.com 1 2025-10-30 2025-10-30
*.membrain.com 1 2025-10-30 2025-10-30
learn.membrain.com 16 2026-06-14 2026-10-10
status.membrain.com 5 2026-05-15 2026-09-11
podcast.membrain.com 4 2026-04-18 2026-08-16
www.membrain.com 8 2026-04-24 2026-08-19

Programmatic access: API GET /v1/hosts/membrain.com (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/membrain.com.