What Websites Can See About You
- Your exact screen resolution, color depth, and pixel ratio—enough to identify your specific monitor
- CPU cores, device memory, and GPU model via WebGL—creates a hardware fingerprint
- Timezone, language preferences, and installed fonts—narrows down your location and setup
- All of this data combined can uniquely identify you even without cookies (browser fingerprinting)
For Developers
- Debug 'works on my machine' issues—copy exact browser/OS info for bug reports
- Test responsive breakpoints—see actual viewport vs screen size difference
- Check API support before using WebGL, WebRTC, or Service Workers in your app
- Verify devicePixelRatio for retina display optimizations
- Monitor JS heap memory usage during performance testing
Privacy Insights
- Canvas and WebGL fingerprinting can track you without cookies
- navigator.hardwareConcurrency reveals your CPU core count
- Connection API exposes your network speed and type (WiFi, 4G, etc.)
- Even your battery level was once exposed (now deprecated for privacy)
- Incognito mode doesn't hide most of this information
Interesting Details Exposed
- maxTouchPoints: 0 = desktop, 5+ = touchscreen device
- deviceMemory: Approximate RAM in GB (2, 4, 8, etc.)
- effectiveType: Your actual connection speed (slow-2g, 2g, 3g, 4g)
- reducedMotion: Whether you prefer less animation (accessibility)