Browser diagnostics hub

Fast, private tools for testing what the browser sees.

Check responsive layouts, read your exact display metrics, and inspect the fingerprint your browser exposes. Every tool below runs on your device, with no sign-up and no uploads.

this browser
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DPR 1 Screen 0x0

Resize the window and these update live. That is the screen size detector, running in the hero.

3diagnostic tools
0 bytessent to any server
100%client side
Nosign-up needed

The toolbox

Pick a tool and use it right here.

Am I responsive and responsive design checker

Open full page
Demo page
Desktop 1280
Laptop 1024
Tablet 768
Phone 375
A demo page is loaded so the viewports work right away. Paste your own URL to test it. Switch to Single device to check one exact breakpoint. Some sites block embedding (an X-Frame-Options or frame-ancestors policy); if a real URL stays blank, the site refused the connection. Open the URL in a new tab.

Why nbpl.net

Built to be quick, honest and completely local.

Nothing leaves your device

Every measurement is taken in the browser with plain web APIs. No accounts, no logging, no data collection.

Instant and lightweight

Static pages with minimal script mean tools open in a blink, even on a phone or a slow connection.

Real results, no theatre

Hashes and metrics come from your actual browser. If a value cannot be read, the tool says so instead of faking it.