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.

8 hosts · 312 ms

HostCertsFirst seenLast seenDNS
swmc.com 11 2025-08-01 2026-09-21 ok
*.swmc.com 11 2025-08-01 2026-09-21 —
api-client-qa.swmc.com 1 2026-07-31 2026-07-31 nxdomain
reno.swmc.com 3 2026-04-21 2026-09-21 ok
www.reno.swmc.com 3 2026-04-21 2026-09-21 ok
eblast.development.swmc.com 2 2025-06-30 2026-05-31 ok
test.swmc.com 2 2026-04-12 2026-09-12 ok
www.swmc.com 2 2026-03-25 2026-08-25 ok

Programmatic access, with DNS A records: API GET /v1/hosts/swmc.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/swmc.com.