External Resource Monitoring
Your website loads scripts, fonts, and styles from third-party CDNs. When they go down, your site breaks — but your server still says "200 OK". upsonar checks what your users actually see, not just your server.
CDNs · Scripts · Fonts · Stylesheets · Per-region checks
Why External Resource Monitoring Matters
CDN Outages Break Your Site
Cloudflare alone handles over 20% of all web traffic. When it or Google Fonts or jsDelivr has issues, your page breaks even though your server is fine. Users see a broken layout, missing functionality, or blank page.
Invisible to Traditional Monitors
Ping-based monitors check your server, not your page. They report "up" while your users see a broken site. Only dependency monitoring catches these failures.
Automatic Discovery
upsonar parses your HTML and finds every external resource automatically. No manual configuration — just add your URL and we discover all dependencies.
What We Monitor
Scan Your Website's Dependencies Now
Enter any URL to see all external resources it loads — CDNs, scripts, fonts, and more. Free, no signup required.
Frequently Asked Questions
Monitor What Your Users Actually See
Free plan includes external resource monitoring for 3 websites. Know when CDNs and third-party services affect your site.
Set up in 30 seconds · Free forever
Last updated: February 2026