Most website problems stay invisible until they cost you: a certificate quietly expires because auto-renewal broke, a deploy drops a security header, a redesign ships images with no alt text. Perimeter checks four things in one scan and grades them — TLS certificate, security headers, DNS/email auth (SPF/DMARC), and WCAG accessibility. Free, no signup. Paid plans re-check daily, alert you when something breaks, and show how to fix each finding. Compliance adds a dated, auditor-ready report.