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.

100 hosts (first page) · 397 ms

HostCertsFirst seenLast seenDNS
action1.com 23 2026-04-04 2026-09-30 ok
*.action1.com 3 2025-07-16 2026-06-16 —
remote.qa-apps-01.action1.com 3 2026-04-13 2026-09-13 ok
*.remote.qa-apps-01.action1.com 3 2026-04-13 2026-09-13 —
app.qa-apps-01.action1.com 3 2026-04-13 2026-09-13 ok
*.app.qa-apps-01.action1.com 3 2026-04-13 2026-09-13 —
pd1-product-01.action1.com 13 2026-04-20 2026-09-30 ok
backend.pd1-product-01.action1.com 1 2026-03-30 2026-03-30 nxdomain
*.backend.pd1-product-01.action1.com 1 2026-03-30 2026-03-30 —
*.website.pd1-product-01.action1.com 1 2026-04-20 2026-04-20 —
static.website.pd1-product-01.action1.com 1 2026-08-07 2026-08-07 ok
storage.website.pd1-product-01.action1.com 1 2026-04-28 2026-04-28 nxdomain
admin.website.pd1-product-01.action1.com 2 2026-08-03 2026-08-03 ok
www.website.pd1-product-01.action1.com 1 2026-04-20 2026-04-20 nxdomain
remote.pd1-product-01.action1.com 3 2026-03-30 2026-08-30 ok
*.remote.pd1-product-01.action1.com 3 2026-03-30 2026-08-30 —
*.research.pd1-product-01.action1.com 3 2026-05-04 2026-10-04 —
i1.research.pd1-product-01.action1.com 2 2026-05-05 2026-06-18 nodata
*.i1.research.pd1-product-01.action1.com 2 2026-05-05 2026-06-18 —
remote.i1.research.pd1-product-01.action1.com 10 2026-05-06 2026-06-22 nxdomain
*.remote.i1.research.pd1-product-01.action1.com 10 2026-05-06 2026-06-22 —
p1.research.pd1-product-01.action1.com 1 2026-05-26 2026-05-26 nxdomain
*.p1.research.pd1-product-01.action1.com 1 2026-05-26 2026-05-26 —
i2.research.pd1-product-01.action1.com 11 2026-05-26 2026-07-29 nodata
*.i2.research.pd1-product-01.action1.com 11 2026-05-26 2026-07-29 —
remote.i2.research.pd1-product-01.action1.com 60 2026-05-27 2026-10-05 nxdomain
*.remote.i2.research.pd1-product-01.action1.com 60 2026-05-27 2026-10-05 —
i3.research.pd1-product-01.action1.com 4 2026-08-06 2026-08-06 nodata
*.i3.research.pd1-product-01.action1.com 4 2026-08-06 2026-08-06 —
remote.i3.research.pd1-product-01.action1.com 5 2026-08-06 2026-08-07 nxdomain
*.remote.i3.research.pd1-product-01.action1.com 5 2026-08-06 2026-08-07 —
i4.research.pd1-product-01.action1.com 1 2026-10-01 2026-10-01 nodata
*.i4.research.pd1-product-01.action1.com 1 2026-10-01 2026-10-01 —
feedback.pd1-product-01.action1.com 2 2026-06-23 2026-06-23 nxdomain
backend.internal.pd1-product-01.action1.com 3 2026-04-01 2026-04-01 nxdomain
*.backend.internal.pd1-product-01.action1.com 2 2026-04-01 2026-04-01 —
roadmap.pd1-product-01.action1.com 2 2026-06-23 2026-06-23 nxdomain
app.pd1-product-01.action1.com 3 2026-03-30 2026-08-30 ok
*.app.pd1-product-01.action1.com 3 2026-03-30 2026-08-30 —
telemetrycf.app.pd1-product-01.action1.com 6 2026-05-24 2026-06-01 nxdomain
telemetry.app.pd1-product-01.action1.com 4 2026-05-05 2026-08-31 ok
features.pd1-product-01.action1.com 2 2026-06-23 2026-06-23 nxdomain
www.pd1-product-01.action1.com 12 2026-04-20 2026-09-30 ok
remote.pd2-product-01.action1.com 3 2026-04-13 2026-09-13 ok
*.remote.pd2-product-01.action1.com 3 2026-04-13 2026-09-13 —
app.pd2-product-01.action1.com 3 2026-04-13 2026-09-13 ok
*.app.pd2-product-01.action1.com 3 2026-04-13 2026-09-13 —
remote.pd3-product-01.action1.com 3 2026-04-13 2026-09-13 ok
*.remote.pd3-product-01.action1.com 3 2026-04-13 2026-09-13 —
app.pd3-product-01.action1.com 3 2026-04-13 2026-09-13 ok
*.app.pd3-product-01.action1.com 3 2026-04-13 2026-09-13 —
remote.qa-product-01.action1.com 3 2026-04-16 2026-09-16 ok
*.remote.qa-product-01.action1.com 3 2026-04-16 2026-09-16 —
app.qa-product-01.action1.com 3 2026-04-16 2026-09-16 ok
*.app.qa-product-01.action1.com 3 2026-04-16 2026-09-16 —
integration-product-01.action1.com 1 2026-04-23 2026-04-23 nodata
remote.integration-product-01.action1.com 2 2026-04-06 2026-09-06 ok
*.remote.integration-product-01.action1.com 2 2026-04-06 2026-09-06 —
tam.integration-product-01.action1.com 2 2026-09-17 2026-09-17 nxdomain
app.integration-product-01.action1.com 2 2026-04-06 2026-09-06 ok
*.app.integration-product-01.action1.com 2 2026-04-06 2026-09-06 —
telemetry.app.integration-product-01.action1.com 4 2026-08-12 2026-08-17 ok
www.integration-product-01.action1.com 1 2026-04-23 2026-04-23 nxdomain
remote.devops-product-01.action1.com 2 2026-04-16 2026-09-16 ok
*.remote.devops-product-01.action1.com 2 2026-04-16 2026-09-16 —
app.devops-product-01.action1.com 1 2026-04-16 2026-04-16 nxdomain
*.app.devops-product-01.action1.com 1 2026-04-16 2026-04-16 —
telemetry.app.devops-product-01.action1.com 2 2026-08-25 2026-08-25 ok
remote.eu.devops-product-01.action1.com 5 2026-05-12 2026-05-14 ok
*.remote.eu.devops-product-01.action1.com 5 2026-05-12 2026-05-14 —
backend.pd1.action1.com 1 2025-09-26 2025-09-26 nodata
*.backend.pd1.action1.com 1 2025-09-26 2025-09-26 —
remote.pd1.action1.com 2 2025-09-26 2025-09-26 nodata
*.remote.pd1.action1.com 2 2025-09-26 2025-09-26 —
app.pd1.action1.com 1 2025-09-26 2025-09-26 nodata
*.app.pd1.action1.com 1 2025-09-26 2025-09-26 —
*.test2-master.pd1.action1.com 7 2025-09-18 2026-05-14 —
ip5.test2-master.pd1.action1.com 2 2026-02-14 2026-02-16 nodata
*.ip5.test2-master.pd1.action1.com 2 2026-02-14 2026-02-16 —
remote.ip5.test2-master.pd1.action1.com 81 2026-03-09 2026-04-22 nxdomain
*.remote.ip5.test2-master.pd1.action1.com 81 2026-03-09 2026-04-22 —
relay.ip5.test2-master.pd1.action1.com 4 2026-03-12 2026-03-12 nxdomain
*.relay.ip5.test2-master.pd1.action1.com 4 2026-03-12 2026-03-12 —
test-master.pd1.action1.com 1 2025-07-10 2025-07-10 nodata
*.test-master.pd1.action1.com 1 2025-09-03 2025-09-03 —
*.prod1.test-master.pd1.action1.com 1 2025-10-29 2025-10-29 —
*.website-test.pd1.action1.com 2 2026-03-16 2026-03-19 —
www.website-test.pd1.action1.com 2 2026-03-16 2026-03-19 nxdomain
www.dev.pd1.action1.com 1 2025-10-16 2025-10-16 nodata
www.pd1.action1.com 1 2026-02-18 2026-02-18 nxdomain
backend.ip1.action1.com 2 2025-08-04 2026-07-05 nodata
*.backend.ip1.action1.com 2 2025-08-04 2026-07-05 —
remote.ip1.action1.com 2 2025-08-04 2026-07-05 nodata
*.remote.ip1.action1.com 2 2025-08-04 2026-07-05 —
app.ip1.action1.com 2 2025-08-04 2026-07-05 nodata
*.app.ip1.action1.com 2 2025-08-04 2026-07-05 —
remote.ea.na-2.action1.com 1 2026-06-22 2026-06-22 nxdomain
*.remote.ea.na-2.action1.com 1 2026-06-22 2026-06-22 —
remote.sa.na-2.action1.com 1 2026-06-22 2026-06-22 nxdomain
*.remote.sa.na-2.action1.com 1 2026-06-22 2026-06-22 —

Showing the first 100 hostnames — sign in with GitHub or Google to page the full list, or use the API with an API key: GET /v1/hosts/action1.com.

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/action1.com.