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.

12 hosts · 285 ms

HostCertsFirst seenLast seenDNS
zelt.app 9 2026-03-11 2026-09-04 ok
*.zelt.app 3 2025-12-07 2026-08-14 —
data.zelt.app 1 2025-12-21 2025-12-21 nxdomain
marketing.zelt.app 1 2026-02-10 2026-02-10 ok
go.zelt.app 1 2025-11-14 2025-11-14 ok
*.go.zelt.app 1 2025-11-14 2025-11-14 —
ni-calculator.zelt.app 4 2026-04-11 2026-08-10 ok
mta-sts.zelt.app 3 2026-05-04 2026-09-23 ok
inst.zelt.app 4 2026-04-17 2026-08-17 ok
tt.zelt.app 4 2025-12-21 2026-09-07 ok
www.zelt.app 5 2026-05-09 2026-09-04 ok
instantly.zelt.app 1 2025-12-18 2025-12-18 ok

Programmatic access, with DNS A records: API GET /v1/hosts/zelt.app (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/zelt.app.