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.

5 hosts · 237 ms

HostCertsFirst seenLast seen
cellenion.com 4 2026-04-19 2026-08-19
lifesciences.cellenion.com 14 2026-05-20 2026-09-15
files.cellenion.com 16 2026-05-29 2026-09-24
meet.cellenion.com 14 2026-05-29 2026-09-24
www.cellenion.com 4 2026-04-19 2026-08-19

Programmatic access: API GET /v1/hosts/cellenion.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/cellenion.com.