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 · 225 ms

HostCertsFirst seenLast seen
dupixent.com 2 2026-03-24 2026-08-24
cpmckservice.dupixent.com 2 2025-08-17 2026-07-18
module.dupixent.com 10 2026-05-23 2026-09-20
load.module.dupixent.com 10 2026-05-20 2026-09-15
iaso-amer.dupixent.com 5 2026-04-21 2026-09-27
www.dupixent.com 2 2026-04-06 2026-09-06

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