The Viewport Size Tester tool lets you quickly check your website at different screen size resolutions.
How to use the Viewport Size Tester Tool
Easily test how any website looks on desktop, tablet, and mobile screens with this simple Viewport Size Tester tool, just enter a URL and preview responsive layouts instantly.
- Enter the Website URL
- In the input field labelled “Website URL”, type or paste the full link of the website you want to test.
- Example: https://example.com
- Click the Green “Test Viewport” Button
- This will generate 3 previews:
- Desktop view (1200px wide)
- Tablet view (768px wide)
- Mobile view (375px wide)
- This will generate 3 previews:
- Scroll Down to View the Previews
- You’ll see how the site looks in each screen size using embedded iframes.
- (Optional) Copy the Preview Code
Click the “Copy Preview Code” button.
A prompt will ask for confirmation. Click OK.
The preview HTML code is copied to your clipboard, you can now paste it wherever you need (e.g., an email or code editor).
Should I test websties on phycial devices
Yes, testing websites on physical devices is highly recommended. While tools like viewport simulators and browser dev tools are useful, they can’t fully replicate real-world behaviour. Physical devices provide accurate insights into performance, touch responsiveness, screen brightness, and actual user experience.
You can test how your website behaves with real network speeds, device-specific bugs, and various operating systems. This helps ensure your site is truly mobile-friendly, loads quickly, and works smoothly across different devices. For best results, combine physical device testing with virtual tools to cover more scenarios and catch issues that may not appear in a simulated environment.
Does this tool work with all web browsers
This tool works with most modern web browsers like Google Chrome, Mozilla Firefox, Microsoft Edge, and Safari.
However, a few things to keep in mind:
Supported: Most HTML5-compliant browsers will run the tool correctly.
iFrames May Not Load: Some websites have security settings (like X-Frame-Options) that block loading in iframes, so they won’t display-even though the tool itself is working.
Outdated Browsers: Very old browsers (like Internet Explorer) may not fully support features like the URL object or clipboard copy.
So yes, the tool works in general, but site previews depend on the website’s iframe policy.
FAQs about Viewport Size Tester Tool
It previews how a website looks on desktop (1200px), tablet (768px), and mobile (375px) viewports using iframes.
Enter a website URL (starting with http:// or https://) and click the “Test Viewport” button to generate the previews.
No. Just open the HTML file in any modern web browser—no installation or plugins required.
No. The tool only works with publicly accessible URLs on the internet.
Some websites block iframe embedding using security headers like X-Frame-Options. This prevents them from loading in the tool.
Yes. After generating the preview, click the “Copy Preview Code” button to copy the HTML snippet.
Yes, the tool itself is responsive and can be used on mobile devices, though testing is more convenient on a desktop.
No. It only shows visual layout changes based on width. It does not simulate touch, CPU performance, or actual mobile browser behaviour.
It works with most modern browsers (Chrome, Firefox, Edge, Safari). Some features like clipboard copy may not work in older browsers.
No. This is a client-side tool, your URL input stays in your browser and is never stored or sent to a server.
Yes, this tool is 100% free to use. It runs entirely in your web browser, requires no downloads or subscriptions, and doesn’t send any data to a server. Just open the file and start testing!
Disclaimer: DCP Web Designers are not liable for damage or loss of profits caused by using the Viewport Size Tester Tool on this page.