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.

8 hosts · 300 ms

HostCertsFirst seenLast seenDNS
altify.app 11 2025-10-23 2026-09-13 ok
*.altify.app 1 2025-10-23 2025-10-23 —
mta-sts.mail.altify.app 4 2026-04-24 2026-07-19 ok
mta-sts.email.altify.app 4 2026-04-11 2026-08-10 ok
admin.altify.app 4 2026-06-08 2026-10-06 ok
join.altify.app 10 2026-05-04 2026-08-31 ok
help.altify.app 5 2026-05-23 2026-09-20 ok
www.altify.app 8 2026-05-18 2026-09-13 ok

Programmatic access, with DNS A records: API GET /v1/hosts/altify.app (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/altify.app.