Responsive Breakpoint Tester

Test responsive design at common breakpoints

🔒 Files never leave your browser

Mode

Note: Some websites block iframe embedding (X-Frame-Options / CSP). If a site appears blank, it may be blocking external embedding.

Preview width: 375px

How to Use Responsive Breakpoint Tester

Enter a website URL or paste HTML.

Switch between Mobile, Tablet, Laptop, Desktop.

See how the site looks at each width.

Why do some sites not load? ▼

Some sites block iframe embedding via X-Frame-Options or CSP headers.

Is there a file size limit? ▼

No strict limit. Processing happens in your browser, so capacity depends on your device memory. Most files work smoothly.

Which browsers are supported? ▼

All modern browsers including Chrome, Firefox, Safari, Edge, and Opera on both desktop and mobile.

Can I use this offline? ▼

Yes. Once the page is loaded, the tool works without an internet connection since all processing is local.

Is my data secure? ▼

Yes. Your data never leaves your browser. Nothing is stored on or transmitted to any server.

Does this work on mobile? ▼

Yes. All AllTools tools are fully responsive and work on phones and tablets.

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