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 · 155 ms

HostCertsFirst seenLast seen
cloud.loyalty.southwest.com 3 2025-09-09 2026-09-07
image.loyalty.southwest.com 5 2025-09-17 2026-10-05
click.loyalty.southwest.com 3 2025-09-09 2026-09-07
view.loyalty.southwest.com 3 2025-09-09 2026-09-06

Programmatic access: API GET /v1/hosts/loyalty.southwest.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/loyalty.southwest.com.