Sentinel

Sentinel is a website monitoring tool for agencies and freelancers managing multiple client sites. It watches client sites around the clock and sends alerts when downtime, SSL issues, DNS changes, or unreachable hosts are detected, so site problems can be noticed before clients do.

Its monitoring features include uptime checks every 30 seconds, SSL monitoring with alerts weeks before expiration, DNS tracking, keyword monitoring for page content or unwanted text, JSON API monitoring, ICMP ping monitoring, TCP port monitoring, heartbeat monitoring for cron jobs and workers, cron job monitoring, and WHOIS domain expiration tracking. The service also includes incident management with automatic timelines and resolution notes, plus public or password-protected status pages with custom domain and branding options. An MCP-based AI assistant feature connects Claude, ChatGPT, or other MCP agents for plain-language incident triage and questions such as whether anything is down.

Sentinel supports alerts via Slack, Email, SMS, Discord, and Microsoft Teams. It presents monitoring from a single dashboard and says new monitors can be added by pasting a URL and choosing checks. The page also states that setup takes 60 seconds, that checks can run from 4 global regions, and that team collaboration uses role-based permissions for developers and account managers.

Pricing includes a free plan with 10 monitors and a 14-day free trial that can be canceled anytime. Paid plans listed on the page are Starter at $14 per month for 25 monitors, Pro at $29 per month for 100 monitors, and Business at $59 per month for 300 monitors. The page describes Sentinel as a website and infrastructure monitoring tool by rootstuff.