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.

19 hosts · 294 ms

HostCertsFirst seenLast seen
gmx.com 1 2026-03-03 2026-03-03
*.gmx.com 1 2026-03-03 2026-03-03
mx00.gmx.com 2 2026-04-14 2026-09-02
i0.gmx.com 1 2025-12-18 2025-12-18
mx01.gmx.com 2 2026-04-14 2026-09-02
dl.gmx.com 1 2025-12-18 2025-12-18
mail.gmx.com 2 2026-04-14 2026-09-02
imap.gmx.com 2 2026-04-14 2026-09-02
pop.gmx.com 2 2026-04-14 2026-09-02
smtp.gmx.com 2 2026-04-14 2026-09-02
*.navigator-pre-bs.gmx.com 2 2025-10-14 2026-09-02
navigator-bs.gmx.com 1 2026-03-03 2026-03-03
*.navigator-bs.gmx.com 1 2026-03-03 2026-03-03
mta-sts.gmx.com 2 2026-03-11 2026-08-17
mout.gmx.com 2 2026-04-14 2026-09-02
www.gmx.com 1 2026-03-03 2026-03-03
*.www.gmx.com 1 2026-03-03 2026-03-03
cad.www.gmx.com 2 2025-08-05 2026-07-07
*.cad.www.gmx.com 2 2025-08-05 2026-07-07

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