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 · 268 ms

HostCertsFirst seenLast seen
schaeffersresearch.com 3 2025-12-17 2026-04-07
*.schaeffersresearch.com 3 2025-12-17 2026-04-07
a.schaeffersresearch.com 2 2025-07-15 2026-06-15
*.a.schaeffersresearch.com 2 2025-07-15 2026-06-15
mta-17-50.a.schaeffersresearch.com 5 2026-05-11 2026-09-09
b.schaeffersresearch.com 1 2025-12-23 2025-12-23
*.b.schaeffersresearch.com 1 2025-12-23 2025-12-23
mta-17-45.b.schaeffersresearch.com 5 2026-05-18 2026-09-16
e.schaeffersresearch.com 1 2026-01-19 2026-01-19
*.e.schaeffersresearch.com 1 2026-01-19 2026-01-19
mta-17-20.e.schaeffersresearch.com 4 2026-04-17 2026-08-15
j.schaeffersresearch.com 2 2025-07-25 2026-06-25
*.j.schaeffersresearch.com 2 2025-07-25 2026-06-25
mta-17-51.j.schaeffersresearch.com 5 2026-05-22 2026-09-20
m.schaeffersresearch.com 1 2025-12-23 2025-12-23
*.m.schaeffersresearch.com 1 2025-12-23 2025-12-23
mta-17-46.m.schaeffersresearch.com 5 2026-05-19 2026-09-16
app.schaeffersresearch.com 12 2026-05-09 2026-09-05
ads.schaeffersresearch.com 15 2026-05-23 2026-09-19
z.schaeffersresearch.com 3 2025-09-11 2026-08-12
*.z.schaeffersresearch.com 3 2025-09-11 2026-08-12
mta-17-37.z.schaeffersresearch.com 4 2026-04-17 2026-08-15

Programmatic access: API GET /v1/hosts/schaeffersresearch.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/schaeffersresearch.com.