Viewport Size Simulator
Emulate device screen sizes visually in the browser. Test responsive designs across different viewport dimensions.
Viewport Settings
Mobile
Tablet
Desktop
Preview
⚠️ Website Loading Limitations
Some websites may not load in the preview due to security restrictions called "X-Frame-Options" or "Content Security Policy" headers that prevent embedding in iframes.
- • Personal websites and blogs
- • Documentation sites
- • Portfolio websites
- • Most static sites
- • GitHub Pages
- • Google, Facebook, Twitter
- • Banking and financial sites
- • E-commerce platforms
- • Sites with strict security
- • Many popular web apps
- • Use browser developer tools (F12 → Device Toolbar)
- • Test with your own websites or development servers
- • Use responsive design testing tools in your browser
- • Try websites that allow iframe embedding
This limitation is a security feature implemented by websites to prevent clickjacking attacks and is not related to this tool's functionality.
About Viewport Size Simulator
A viewport size simulator is an essential web development tool that allows developers to test and preview how their websites appear across different device screen sizes and resolutions. This tool emulates various device viewports including mobile phones, tablets, desktops, and custom dimensions, helping ensure optimal responsive design implementation without needing physical devices.
Why use a Viewport Size Simulator?
Using a viewport size simulator streamlines responsive design testing, saves time and resources by eliminating the need for multiple physical devices, and ensures consistent user experience across all screen sizes. It helps identify layout issues, optimize media queries, and validate that your responsive design works properly before deployment, ultimately improving website accessibility and user satisfaction.
Who is it for?
This tool is perfect for web developers creating responsive websites, UI/UX designers testing interface layouts across devices, quality assurance testers validating cross-device compatibility, and digital agencies ensuring client websites work seamlessly on all screen sizes. It's also valuable for anyone involved in web development who needs to verify responsive design functionality.
How to use the tool
- Enter the website URL or load your local development site
- Select from preset device dimensions or enter custom width and height values
- Click simulate to view how your website appears in the selected viewport size
- Test multiple device sizes to ensure your responsive design works correctly
- Use the tool to identify and fix any layout issues across different screen dimensions
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