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.

34 hosts · 299 ms

HostCertsFirst seenLast seen
read.ai 10 2026-04-16 2026-08-12
*.read.ai 18 2025-06-25 2026-09-29
*.infra.read.ai 13 2025-06-25 2026-09-29
*.e.read.ai 2 2025-10-29 2026-09-29
mta-sts.send.re.read.ai 2 2026-08-17 2026-08-17
links.re.read.ai 1 2026-08-24 2026-08-24
mta-sts.re.read.ai 2 2026-08-17 2026-08-17
*.preview-internal-lab.staging.read.ai 1 2026-09-03 2026-09-03
*.metrics.preview-internal-lab.staging.read.ai 1 2026-09-04 2026-09-04
*.discovery.preview-internal-lab.staging.read.ai 1 2026-09-04 2026-09-04
*.api.preview-internal.staging.read.ai 2 2026-09-14 2026-09-14
*.metrics.preview-internal.staging.read.ai 3 2026-09-04 2026-09-21
*.discovery.preview-internal.staging.read.ai 4 2026-09-04 2026-09-15
preview-router.staging.read.ai 4 2026-08-12 2026-08-14
preview.staging.read.ai 2 2026-08-11 2026-08-11
*.preview.staging.read.ai 2 2026-08-11 2026-08-11
*.api.preview.staging.read.ai 4 2026-08-12 2026-08-14
app.preview.staging.read.ai 4 2026-09-14 2026-09-23
*.app.preview.staging.read.ai 4 2026-09-14 2026-09-23
*.broadcast.preview.staging.read.ai 2 2026-09-14 2026-09-14
xr-api.read.ai 2 2025-08-21 2026-07-22
sam-alb.internal.read.ai 1 2025-12-29 2025-12-29
ram-api.internal.read.ai 1 2026-01-02 2026-01-02
sam-api.internal.read.ai 3 2025-12-29 2025-12-30
sam-endpoint.internal.read.ai 1 2025-12-29 2025-12-29
status.read.ai 5 2026-04-13 2026-10-08
fleet.read.ai 1 2025-11-29 2025-11-29
munki.fleet.read.ai 1 2026-01-14 2026-01-14
op.fleet.read.ai 3 2026-03-18 2026-08-18
get.read.ai 9 2026-05-19 2026-09-14
support.read.ai 3 2026-06-07 2026-08-06
trust.read.ai 6 2026-05-22 2026-09-17
stg-next.read.ai 1 2026-05-19 2026-05-19
www.read.ai 11 2026-05-18 2026-09-14

Programmatic access: API GET /v1/hosts/read.ai (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/read.ai.