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.

22 hosts · 239 ms

HostCertsFirst seenLast seen
mod.io 35 2026-04-18 2026-10-13
*.mod.io 23 2026-05-13 2026-09-21
*.old.mod.io 6 2026-05-26 2026-09-21
commerce.mod.io 2 2026-01-31 2026-02-04
blog.mod.io 4 2026-05-26 2026-07-24
auth.mod.io 3 2026-03-18 2026-08-18
api.mod.io 8 2025-08-09 2026-07-11
newsletter.mod.io 6 2026-04-21 2026-08-03
metrics.mod.io 3 2025-09-14 2026-08-15
docs.mod.io 2 2026-03-02 2026-07-18
slides.mod.io 5 2026-05-16 2026-09-14
cf-api-us.mod.io 4 2025-08-09 2026-07-11
status.mod.io 1 2026-01-16 2026-01-16
support.mod.io 5 2026-06-11 2026-10-09
test.mod.io 13 2026-04-29 2026-08-25
*.test.mod.io 10 2025-06-18 2026-10-05
commerce.test.mod.io 5 2025-12-08 2026-08-26
commerce-internal.test.mod.io 1 2025-12-11 2025-12-11
*.ws.test.mod.io 4 2026-08-24 2026-08-24
trust.mod.io 10 2026-05-06 2026-09-01
cf-api-eu.mod.io 4 2025-08-09 2026-07-11
*.legacy.mod.io 6 2026-05-26 2026-09-21

Programmatic access: API GET /v1/hosts/mod.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/mod.io.