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 · 364 ms

HostCertsFirst seenLast seenDNS
synax.io 61 2026-04-18 2026-09-14 ok
*.synax.io 47 2026-04-18 2026-09-14 —
login.synax.io 4 2026-06-04 2026-07-05 ok
status.synax.io 10 2026-05-02 2026-08-28 ok
jit.synax.io 10 2026-04-16 2026-08-12 ok
support.synax.io 10 2026-05-16 2026-09-12 ok
test.synax.io 6 2026-05-03 2026-08-29 ok
www.synax.io 14 2026-04-17 2026-08-30 ok

Programmatic access, with DNS A records: API GET /v1/hosts/synax.io (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/synax.io.