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    Responsive Design TesterFree Online Developer Tool

    Responsive Design Tester is a free online developer tool. Preview how your website looks on different devices and screen sizes.

    Note: Some websites may block being displayed in iframes due to security policies.

    Device Presets
    Custom Size
    Controls
    iPhone SE iconiPhone SE
    375 × 667 (90% zoom)

    No Website Loaded

    Enter a URL above to preview how it looks on different devices

    100% Private100% Private
    InstantInstant
    Any DeviceAny Device
    Free ForeverFree Forever
    How to useHow to use & Tips

    Steps

    1. 1Enter your website URL in the input field
    2. 2Click 'Load Website' to preview
    3. 3Select different device presets from the sidebar
    4. 4Use the rotate button to switch between portrait and landscape
    5. 5Set custom dimensions for specific testing needs

    Use Cases

    • -Testing website responsiveness before launch
    • -Checking mobile layout for client presentations
    • -Verifying CSS breakpoints work correctly
    • -Previewing sites on specific device sizes
    • -Quick cross-device visual checks

    About Responsive Design Tester

    Everything you need to know about this tool and how to get the most out of it.

    What is Responsive Design Tester?

    What is Responsive Design Tester?

    The Responsive Design Tester lets you preview any website at different screen sizes and device resolutions. Enter a URL and instantly see how it looks on iPhones, iPads, Android phones, and desktop screens — without needing physical devices.
    How Responsive Design Tester Works

    How Responsive Design Tester Works

    Enter a URL and click Load. The tool renders the website in an iframe scaled to match your selected device's dimensions. Switch between device presets, rotate between portrait and landscape, or enter custom dimensions. Note: some sites block iframe embedding for security reasons.
    Why Use Responsive Design Tester?

    Why Use Responsive Design Tester?

    Over 60% of web traffic comes from mobile devices. Testing responsive design is essential before launch. This tool provides a quick visual check across popular device sizes without needing browser DevTools or physical devices.
    Tips

    Tips & Best Practices

    • 1Test your site at 375px (iPhone SE) — the most common small screen size
    • 2Check both portrait and landscape orientations using the Rotate button
    • 3Some sites block iframes — try opening them in a new tab instead
    • 4Use custom dimensions to test specific breakpoints in your CSS
    • 5For deeper testing, use browser DevTools (F12) for full emulation

    Frequently Asked Questions