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.

25 hosts · 277 ms

HostCertsFirst seenLast seenDNS
spare.com 38 2026-04-24 2026-09-27 ok
*.spare.com 14 2026-04-24 2026-08-21 —
connectlive26.spare.com 6 2026-06-11 2026-08-09 ok
apta.spare.com 2 2026-08-24 2026-08-24 ok
tnc.spare.com 4 2026-06-24 2026-08-22 ok
sightline-api-gke.spare.com 2 2026-06-23 2026-06-23 nxdomain
sightline.spare.com 4 2026-06-03 2026-08-25 ok
sightline-staging.spare.com 2 2026-06-26 2026-08-19 ok
sightline-api-staging.spare.com 2 2026-06-19 2026-06-19 nxdomain
*.sightline-ops-staging.spare.com 4 2026-06-19 2026-08-19 —
base.rider.staging.spare.com 1 2026-09-03 2026-09-03 ok
billing.spare.com 1 2026-08-14 2026-08-14 ok
ai.spare.com 2 2026-09-25 2026-09-25 ok
sightline-api.spare.com 6 2026-04-21 2026-06-19 nxdomain
scheduler.spare.com 11 2026-05-30 2026-09-25 ok
pages.spare.com 8 2026-05-05 2026-08-31 ok
outcomes.spare.com 10 2026-04-12 2026-08-09 ok
demos.spare.com 10 2026-05-12 2026-09-08 ok
*.sightline-ops.spare.com 4 2026-06-23 2026-08-22 —
success.spare.com 10 2026-04-12 2026-08-09 ok
mta-sts.spare.com 10 2026-04-28 2026-08-24 ok
enablement.spare.com 7 2026-05-08 2026-09-26 ok
trust.spare.com 2 2026-01-21 2026-01-21 ok
new.spare.com 6 2026-04-13 2026-08-09 ok
www.spare.com 13 2026-06-03 2026-09-30 ok

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