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.

9 hosts · 294 ms

HostCertsFirst seenLast seen
realtimeregister.com 3 2025-07-27 2026-04-08
kb.realtimeregister.com 5 2026-04-30 2026-08-28
adac.realtimeregister.com 3 2025-07-27 2026-04-08
dm.realtimeregister.com 3 2025-07-27 2026-04-08
admin.realtimeregister.com 4 2026-06-03 2026-10-02
metrics.realtimeregister.com 5 2026-05-09 2026-09-06
load.metrics.realtimeregister.com 8 2026-05-08 2026-09-03
status.realtimeregister.com 5 2026-05-07 2026-09-09
www.realtimeregister.com 3 2025-07-27 2026-04-08

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