Online Tool Store
Responsive Breakpoint Tester
Preview a page at standard responsive breakpoints - mobile, tablet, laptop, and desktop widths - in an embedded frame.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Some sites block iframe embedding (X-Frame-Options) and won't render below.
How the responsive breakpoint tester works
- Enter the URL of the page you want to preview.
- Choose a standard breakpoint from the dropdown.
- View the page rendered at that exact width.
FAQ
What breakpoints are included?
Mobile S (320px), Mobile L (425px), Tablet (768px), Laptop (1024px), and Desktop (1440px) - common industry-standard reference widths for responsive design.
Why can't I preview every website?
Some sites set the X-Frame-Options or Content-Security-Policy header to block being displayed inside an iframe, which prevents the preview from loading - a security setting on their end.
Is this the same as browser dev tools?
It's a simpler, quicker alternative for eyeballing standard breakpoints - browser dev tools offer more precision and additional features like touch emulation.
Can I preview a page I'm developing locally?
Only if it's reachable via a URL your browser can load in an iframe - a local file:// path generally won't work due to browser security restrictions.
How we compare
| Feature | Online Tool Store | Resizing your browser window | Browser dev tools device mode |
|---|---|---|---|
| Standard preset widths | ✓ | ✗ | ✓ |
| No dev tools panel needed | ✓ | ✓ | ✗ |
| Exact pixel-precise dimensions | ✓ | ✗ | ✓ |
A fast way to eyeball a design at the most common device breakpoints without opening dev tools.