Visual Sentinel is a six-layer website monitoring platform for public websites, web applications, APIs, and client portfolios. It combines HTTP uptime, performance and Core Web Vitals, SSL certificate and domain expiry, DNS change detection, rendered browser screenshot comparisons, and critical content assertions. Visual Sentinel is designed to catch failures that ordinary ping monitors miss, including blank renders, missing CTAs, broken layouts, defacement, injected content, and unexpected page changes that still return 200 OK. Incident records keep the response, timeline, and visual evidence together. Teams can alert through email, Slack, Discord, Telegram, WhatsApp, Microsoft Teams, PagerDuty, Opsgenie, webhooks, and browser push according to plan. Additional features include server monitoring, API monitoring, status pages, client reports, Google and Cloudflare integrations, an Android companion, REST API, and MCP tools.