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.

7 hosts · 343 ms

HostCertsFirst seenLast seenDNS
roberthalf.co.uk 2 2026-01-25 2026-01-26 ok
*.roberthalf.co.uk 2 2026-01-25 2026-01-26 —
www.m.roberthalf.co.uk 1 2026-01-26 2026-01-26 ok
tags.roberthalf.co.uk 2 2025-07-02 2026-06-02 ok
collect.roberthalf.co.uk 2 2025-07-02 2026-06-02 ok
timesheet.roberthalf.co.uk 2 2025-09-09 2026-01-21 ok
dev-timesheet.roberthalf.co.uk 5 2025-08-14 2026-09-09 ok

Programmatic access, with DNS A records: API GET /v1/hosts/roberthalf.co.uk (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/roberthalf.co.uk.