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.

29 hosts · 222 ms

HostCertsFirst seenLast seen
passby.com 25 2026-04-24 2026-10-05
*.passby.com 19 2026-04-24 2026-09-15
chatgpt-connector-1-5.passby.com 2 2026-07-17 2026-09-11
claude-connector-1-7.passby.com 3 2026-07-31 2026-09-23
copilot-connector-1-7.passby.com 3 2026-07-31 2026-09-25
chatgpt-connector-1-7.passby.com 3 2026-07-31 2026-09-24
data.passby.com 10 2026-06-13 2026-10-02
almanac.passby.com 7 2026-05-12 2026-10-02
beta-almanac.passby.com 5 2026-04-28 2026-09-01
legacy-almanac.passby.com 1 2026-10-02 2026-10-02
internal-api.passby.com 6 2026-05-12 2026-10-02
email.mail.passby.com 5 2026-06-05 2026-10-03
internal-admin.passby.com 6 2026-05-12 2026-10-02
vpn.passby.com 2 2026-10-07 2026-10-07
help.passby.com 12 2026-05-15 2026-09-11
copilot-connector.passby.com 5 2026-05-14 2026-09-29
sales.passby.com 6 2026-05-02 2026-08-28
qm-harness.passby.com 1 2026-08-04 2026-08-04
support.passby.com 16 2026-05-28 2026-09-23
claude-mcp-dev.passby.com 1 2026-09-08 2026-09-08
copilot-mcp-dev.passby.com 1 2026-09-08 2026-09-08
chatgpt-mcp-dev.passby.com 1 2026-09-08 2026-09-08
claude-connector-dev.passby.com 3 2026-07-30 2026-09-24
copilot-connector-dev.passby.com 3 2026-07-29 2026-09-20
chatgpt-connector-dev.passby.com 2 2026-06-29 2026-08-22
claude-mcp-preview.passby.com 1 2026-09-08 2026-09-08
copilot-mcp-preview.passby.com 1 2026-09-08 2026-09-08
chatgpt-mcp-preview.passby.com 1 2026-09-08 2026-09-08
www.passby.com 6 2026-04-29 2026-10-05

Programmatic access: API GET /v1/hosts/passby.com (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/passby.com.