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.

18 hosts · 344 ms

HostCertsFirst seenLast seen
tandem.vet 8 2025-07-22 2026-09-13
data.tandem.vet 5 2026-04-17 2026-09-28
clinic.tandem.vet 2 2025-08-18 2026-07-19
dev.clinic.tandem.vet 2 2025-08-20 2026-07-21
wifi.tandem.vet 4 2025-08-04 2026-07-05
api.tandem.vet 4 2025-08-18 2026-09-23
dev.api.tandem.vet 2 2025-08-20 2026-07-21
mdm.tandem.vet 5 2026-05-07 2026-09-04
platform.tandem.vet 4 2026-08-11 2026-10-05
resources.tandem.vet 8 2026-07-21 2026-09-18
forms.tandem.vet 4 2026-04-21 2026-08-19
dev.events.tandem.vet 2 2025-10-06 2026-09-06
mta-sts.tandem.vet 3 2026-04-28 2026-09-18
event.tandem.vet 2 2025-09-09 2026-08-10
api.dev.tandem.vet 1 2026-07-24 2026-07-24
www.tandem.vet 11 2025-07-22 2026-09-12
pay.tandem.vet 3 2025-07-22 2026-07-23
www.pay.tandem.vet 3 2025-07-22 2026-07-23

Programmatic access: API GET /v1/hosts/tandem.vet (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/tandem.vet.