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.

11 hosts · 321 ms

HostCertsFirst seenLast seenDNS
onceupon.se 5 2026-05-16 2026-09-16 ok
brand.onceupon.se 5 2026-05-19 2026-09-15 ok
e.onceupon.se 5 2026-04-28 2026-09-27 ok
clicks.info.onceupon.se 2 2025-08-14 2026-07-15 ok
influencers.onceupon.se 1 2025-11-16 2025-11-16 ok
staging.assets.onceupon.se 3 2026-05-22 2026-09-06 ok
dev.assets.onceupon.se 3 2026-05-23 2026-09-06 ok
reports.onceupon.se 1 2025-11-16 2025-11-16 ok
clicks.news.onceupon.se 2 2025-08-14 2026-07-15 ok
www.onceupon.se 5 2026-05-14 2026-09-14 ok
summary.onceupon.se 1 2025-11-16 2025-11-16 ok

Programmatic access, with DNS A records: API GET /v1/hosts/onceupon.se (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/onceupon.se.