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.

41 hosts · 350 ms

HostCertsFirst seenLast seen
online-a.com 2 2025-08-22 2026-08-19
nyukai-test01.online-a.com 3 2025-10-09 2026-08-27
api-test01.online-a.com 3 2025-09-12 2026-08-19
sp-test01.online-a.com 1 2025-10-09 2025-10-09
www-test01.online-a.com 1 2025-10-09 2025-10-09
nyukai-test02.online-a.com 1 2025-10-09 2025-10-09
api-test02.online-a.com 3 2025-09-12 2026-08-19
sp-test02.online-a.com 1 2025-10-09 2025-10-09
www-test02.online-a.com 1 2025-10-09 2025-10-09
nyukai-reg2.online-a.com 3 2026-03-17 2026-08-19
api-reg2.online-a.com 3 2026-03-17 2026-08-19
sp-reg2.online-a.com 3 2026-03-17 2026-08-19
www-reg2.online-a.com 5 2026-03-17 2026-08-19
gw2reg2.online-a.com 3 2026-03-17 2026-08-19
b2breg2.online-a.com 3 2026-03-17 2026-08-19
gw2.online-a.com 3 2025-08-21 2026-08-19
biz2.online-a.com 4 2025-07-25 2026-08-27
nyukai-test03.online-a.com 1 2025-10-09 2025-10-09
api-test03.online-a.com 3 2025-09-12 2026-08-19
sp-test03.online-a.com 1 2025-10-09 2025-10-09
www-test03.online-a.com 1 2025-10-09 2025-10-09
nyukai-test04.online-a.com 3 2025-09-12 2026-08-19
api-test04.online-a.com 3 2025-09-12 2026-08-19
sp-test04.online-a.com 3 2025-09-12 2026-08-19
www-test04.online-a.com 3 2025-09-12 2026-08-19
nyukai-test05.online-a.com 3 2025-09-12 2026-08-19
api-test05.online-a.com 3 2025-09-12 2026-08-19
sp-test05.online-a.com 4 2025-09-12 2026-08-19
www-test05.online-a.com 3 2025-09-12 2026-08-19
b2b.online-a.com 3 2025-08-21 2026-08-19
nyukai-reg.online-a.com 3 2025-07-09 2026-07-07
api-reg.online-a.com 1 2025-10-09 2025-10-09
sp-reg.online-a.com 1 2025-10-09 2025-10-09
www-reg.online-a.com 5 2025-07-09 2026-08-27
nyukai.online-a.com 3 2025-08-22 2026-08-19
api.online-a.com 1 2026-02-12 2026-02-12
sp.online-a.com 1 2025-10-09 2025-10-09
devops.online-a.com 1 2025-10-09 2025-10-09
gw2test.online-a.com 2 2025-07-09 2026-07-07
b2btest.online-a.com 2 2025-07-09 2026-07-07
www.online-a.com 2 2025-08-22 2026-08-19

Programmatic access: API GET /v1/hosts/online-a.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/online-a.com.