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.

13 hosts · 313 ms

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HostCertsFirst seenLast seen
mfour.com 6 2025-08-06 2026-09-18
*.mfour.com 7 2025-08-06 2026-09-04
omnitrafficdata.mfour.com 10 2026-05-19 2026-09-15
*.api.mfour.com 4 2025-10-04 2026-09-04
email.mail.mfour.com 5 2026-05-03 2026-08-31
go.mfour.com 8 2026-04-24 2026-08-19
agents.mfour.com 1 2026-01-11 2026-01-11
reports.mfour.com 4 2026-05-01 2026-09-02
get.mfour.com 10 2026-06-05 2026-10-01
*.test.mfour.com 4 2025-07-10 2026-06-24
*.api.test.mfour.com 4 2025-07-10 2026-06-12
*.dev.mfour.com 4 2025-08-16 2026-09-18
*.api.dev.mfour.com 4 2025-07-09 2026-07-22

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