VisualSentinel is an external website monitoring platform that helps agencies, SaaS teams, ecommerce operators, and developers catch website failures before customers report them. It combines uptime, performance, SSL, DNS, visual change, and content integrity monitoring in one dashboard. Real-browser screenshot comparisons detect broken layouts and missing content even when a page still returns 200 OK. The service also includes API and endpoint checks, page-level synthetic monitoring, server monitoring, incident evidence, public status pages, domain expiry reminders, and alerts through email, Slack, Discord, WhatsApp, Telegram, Microsoft Teams, PagerDuty, Opsgenie, webhooks, and Prometheus Alertmanager. A permanent free plan includes three HTTP and SSL monitors, and paid plans start at $6 per month.