Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

3 hosts · 216 ms

HostCertsFirst seenLast seenDNS
txns.comms.westernunion.com 5 2025-10-03 2026-06-18 nodata
bounce.txns.comms.westernunion.com 5 2025-10-03 2026-06-18 ok
track.txns.comms.westernunion.com 5 2025-10-03 2026-06-18 ok

Programmatic access, with DNS A records: API GET /v1/hosts/txns.comms.westernunion.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/txns.comms.westernunion.com.