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.

21 hosts · 296 ms

HostCertsFirst seenLast seen
itfortress.com 17 2026-04-28 2026-10-07
*.itfortress.com 10 2026-04-28 2026-10-07
psa.itfortress.com 8 2026-04-23 2026-08-19
data.itfortress.com 8 2026-05-14 2026-09-09
dmarc.itfortress.com 4 2025-07-18 2026-07-17
*.dmarc.itfortress.com 4 2025-07-18 2026-07-17
landing.itfortress.com 2 2026-08-18 2026-08-18
crm.itfortress.com 14 2026-06-05 2026-10-02
guardian.itfortress.com 10 2026-05-07 2026-09-03
mailguardian.itfortress.com 12 2026-06-06 2026-10-02
app.itfortress.com 10 2026-05-01 2026-08-27
filter.itfortress.com 5 2026-05-02 2026-09-06
proposals.itfortress.com 1 2026-08-26 2026-08-26
backups.itfortress.com 5 2026-05-11 2026-09-08
mta-sts.itfortress.com 2 2026-06-04 2026-08-14
oversight.itfortress.com 12 2026-06-08 2026-10-04
support.itfortress.com 2 2026-09-29 2026-10-06
www.itfortress.com 6 2026-06-17 2026-10-01
pbx.itfortress.com 3 2026-05-20 2026-08-13
mta-sts.pbx.itfortress.com 2 2026-06-15 2026-08-25
pay.itfortress.com 5 2026-05-30 2026-09-30

Programmatic access: API GET /v1/hosts/itfortress.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/itfortress.com.