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.

18 hosts · 351 ms

HostCertsFirst seenLast seenDNS
atom.com 34 2026-04-09 2026-10-03 ok
*.atom.com 22 2026-04-26 2026-09-19 —
public.atom.com 7 2026-07-28 2026-09-25 ok
img.atom.com 11 2026-04-27 2026-08-31 ok
r2-img.atom.com 3 2026-09-16 2026-09-16 ok
feedback.atom.com 6 2026-05-06 2026-09-01 ok
helpdesk.atom.com 2 2026-04-02 2026-09-02 ok
discussion.atom.com 4 2026-04-11 2026-08-09 ok
crypto.atom.com 3 2026-07-18 2026-09-15 ok
mcp.atom.com 5 2026-05-03 2026-09-04 ok
registrar.atom.com 7 2026-06-01 2026-09-30 ok
analytics.atom.com 12 2026-04-09 2026-10-03 ok
apidocs.atom.com 4 2026-04-21 2026-08-23 ok
careers.atom.com 5 2026-05-31 2026-09-28 ok
mta-sts.atom.com 4 2026-04-19 2026-08-16 ok
status.atom.com 5 2026-04-10 2026-10-05 ok
api-dev.atom.com 5 2026-05-13 2026-09-08 ok
pay.atom.com 9 2026-04-21 2026-08-17 ok

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