See your website on every screen.
Paste any web address and view it on a phone, tablet, laptop and desktop at the real screen widths, rotate it, and catch the page that slides sideways on a phone before your customers do. Free, with no account, and nothing is uploaded.
Four steps. About two minutes.
Each frame is the actual width of the device, so your responsive breakpoints trigger the way they do on a real screen. Fit mode only scales the frame down so it fits your monitor.
- 01
Paste your page address
Type or paste any web address into the box and press Enter. Pages are loaded straight from your site, so you always see the live version.
- 02
Pick a device or press All
Choose phone, small Android, narrow phone, tablet, laptop or desktop. All shows phone, tablet and laptop side by side.
- 03
Rotate and check
Rotate phones and tablets to landscape, then watch the overflow badge for any page that is wider than the screen.
- 04
Fix, reload and repeat
Change your code, press R to reload, and check again. Copy link gives you a shareable address that opens the same page.
Catch the sideways slide.
A browser cannot read another site's layout from outside, so the tester asks your page to report its own width. Paste this once into your site's shared script or head. Every frame then shows a badge: No sideways scroll, or Overflow +310px when something is wider than the screen. It stays silent for normal visitors.
Responsive testing, answered.
Quick answers on how the tool works and where its limits are.
Is the responsive design tester free?
Yes. It is free to use, needs no login or account, and has no usage limit. It runs entirely in your browser.
Does the tool upload or store my website?
No. Your page loads straight from its own server into frames in your browser. The last URL and your layout choices are kept only in your own browser storage so the tool can reopen where you left off.
Why is my preview blank?
Some websites tell browsers not to display them inside frames, using an X-Frame-Options header or a Content-Security-Policy frame-ancestors rule. Those pages show blank here. An https page also cannot frame an http:// address. Most small business and static sites, including GitHub Pages and Cloudflare Pages, allow framing by default.
Is this the same as testing on a real phone?
It is accurate for layout. Each frame is the real device width, so your media queries and responsive breakpoints fire exactly as they would on that screen. It does not reproduce touch behaviour, browser toolbars or iOS Safari quirks, so do a final check on a real device.
How do I find a page that slides sideways on a phone?
Add the small overflow checker script shown on this page to your site. Each frame then shows a badge with No sideways scroll, or Overflow plus the number of pixels the page is too wide. The script does nothing for normal visitors.
Which screen sizes does it show?
Phone at 390 by 844, small Android at 360 by 740, a 320 pixel narrow phone, tablet at 820 by 1180, laptop at 1366 by 768 and desktop at 1920 by 1080. Phones and tablets can be rotated to landscape, and the All view shows phone, tablet and laptop side by side.
Want a site that passes on every device?
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