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.

11 hosts · 279 ms

HostCertsFirst seenLast seenDNS
workfeed.io 9 2026-04-23 2026-09-13 ok
*.workfeed.io 8 2026-04-23 2026-09-13 —
d.workfeed.io 5 2026-05-30 2026-09-27 ok
load.d.workfeed.io 11 2026-05-28 2026-09-23 ok
stage.workfeed.io 2 2026-09-28 2026-09-28 ok
app.workfeed.io 3 2026-05-30 2026-09-24 ok
docs.workfeed.io 5 2026-04-29 2026-08-28 ok
mta-sts.workfeed.io 5 2026-06-01 2026-09-29 ok
status.workfeed.io 4 2026-04-10 2026-08-08 ok
dev.workfeed.io 5 2026-04-19 2026-08-17 ok
www.workfeed.io 1 2026-05-07 2026-05-07 ok

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