Enter a domain and get an instant, passive map of its internet-facing exposure — forgotten subdomains, expiring certs, missing security headers, and dangling DNS that could be hijacked.
| subdomains | Every host an attacker can enumerate from public CT logs. |
| tls | Expired, expiring-soon, or self-signed certificates. |
| headers | Missing HSTS / CSP / anti-clickjacking headers. |
| takeover | Dangling DNS records pointing at unclaimed services. |
A new staging subdomain. A cert nobody renewed. A DNS record still pointing at a service you decommissioned. Each one is an opening — and the person responsible usually finds out after it's exploited, because nobody's watching the edge.
Enterprise attack-surface tools exist, but they're priced and designed for security teams with a budget and a SOC. If you're a founder or a 20-person company, you get the same exposure with none of the visibility.
Perimeter is built for that gap: self-serve, opinionated, and focused on what changed — not a 400-row dump, just "here's what's newly exposed since last week." It runs continuously and surfaces the one thing that matters before it becomes an incident.
Change-focused alerts — what's newly exposed since last week, not a 400-row dump.
Verify a domain via DNS and you're monitoring. Nothing to deploy.
SMB pricing, not an enterprise ASM contract.
Re-scans on a schedule; you only act when something actually changes.
No. Continuous monitoring requires DNS-TXT proof of ownership. The free one-time scan is passive (public CT logs, DNS, standard web requests).
The monitoring product is gated behind verification and identifies its scanner. The free scan is passive and behaves like a browser visiting your own site.
No. Add a DNS record to verify ownership and Perimeter handles the rest.
It maps your external attack surface and what changed — discovery and exposure, not deep penetration testing.
Your exposure changes every time you ship. Continuous monitoring watches it daily and alerts you the moment something new appears — coming soon.