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 · 329 ms

HostCertsFirst seenLast seenDNS
coursehero.com 29 2025-06-12 2026-10-06 ok
*.coursehero.com 24 2025-09-25 2026-10-06 —
gitlab.coursehero.com 3 2025-06-07 2026-06-07 ok
qb.coursehero.com 10 2026-04-18 2026-08-14 ok
www-waf.coursehero.com 2 2025-06-07 2026-06-07 nxdomain
ci.coursehero.com 5 2025-06-07 2026-06-27 ok
wiki.coursehero.com 4 2026-04-14 2026-09-23 ok
mi.coursehero.com 6 2026-05-30 2026-10-04 ok
gtm.coursehero.com 2 2026-04-02 2026-09-02 ok
helpdocs.coursehero.com 5 2026-05-11 2026-09-10 ok
assets.coursehero.com 2 2025-07-12 2026-06-12 ok
dev-assets.coursehero.com 2 2025-07-12 2026-06-12 ok
*.dev-assets.coursehero.com 2 2025-07-12 2026-06-12 —
*.assets.coursehero.com 2 2025-07-12 2026-06-12 —
events.coursehero.com 5 2026-04-22 2026-08-20 ok
git.coursehero.com 6 2025-06-07 2026-06-27 ok
support.coursehero.com 5 2026-05-20 2026-09-17 ok
dev.coursehero.com 4 2025-07-30 2026-08-02 ok
*.dev.coursehero.com 4 2025-07-30 2026-08-02 —
qb.dev.coursehero.com 6 2026-05-08 2026-09-03 ok
codereview.coursehero.com 5 2025-06-07 2026-06-27 nxdomain
wikinew.coursehero.com 3 2026-05-19 2026-09-02 ok
www.coursehero.com 3 2025-06-12 2026-06-30 ok
waf-www.coursehero.com 3 2025-08-27 2026-06-27 nxdomain
google-jobs-verify.coursehero.com 5 2026-06-03 2026-08-18 ok

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