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.

20 hosts · 192 ms

HostCertsFirst seenLast seen
captions.ai 55 2026-05-08 2026-10-02
*.captions.ai 20 2026-05-18 2026-10-02
share.captions.ai 3 2026-05-26 2026-09-08
api.captions.ai 5 2026-05-11 2026-10-09
l.captions.ai 4 2026-05-01 2026-10-08
am.captions.ai 8 2026-05-31 2026-09-26
*.am.captions.ai 8 2026-05-31 2026-09-26
go.captions.ai 3 2026-07-09 2026-09-11
mcp.captions.ai 5 2026-08-11 2026-10-09
help.captions.ai 6 2026-07-13 2026-09-10
app.captions.ai 4 2026-05-31 2026-09-18
as.captions.ai 10 2026-05-31 2026-09-26
*.as.captions.ai 10 2026-05-31 2026-09-26
sales.captions.ai 8 2026-05-02 2026-07-06
web-tools.captions.ai 3 2026-05-29 2026-09-17
get.captions.ai 14 2026-05-11 2026-09-06
checkout.captions.ai 10 2026-04-21 2026-08-17
text.captions.ai 11 2026-05-31 2026-09-26
api-dev.captions.ai 5 2026-05-11 2026-10-09
www.captions.ai 7 2026-05-08 2026-09-03

Programmatic access: API GET /v1/hosts/captions.ai (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/captions.ai.