Responsive Design Tester — Preview Any Website on Any Device

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About this tool

Free Responsive Website Preview Tool

Responsive Preview Tool is a free browser-based testing tool that loads any publicly accessible website inside a resizable iframe at exact device viewport widths — letting you test responsive layouts, verify breakpoints, and spot cross-device issues without resizing your browser window or switching between physical devices. Modern web design demands that every page look correct across a wide range of viewports: a typical user base spans 320px mobile phones, 390–428px large smartphones, 768px tablets, 1024px iPad Pro, 1280–1440px laptops, and 1920px widescreen monitors. This tool covers that entire range with 10 device presets. A key feature is shareable ?link= URLs — when you paste a URL and preview it, the page URL updates to include a ?link= parameter encoding the target address, so you can share a single link with a client or teammate that opens the preview immediately without re-entering the URL. Additional features include portrait/landscape orientation flip, custom width×height input for arbitrary viewport sizes, zoom controls from 25% to fit-to-window, a breakpoint ruler highlighting the major CSS breakpoints, and multiple canvas background options.

Features

  • 10 device presets — Mobile S 320px through Wide 2K 1920×1080 covering the full common viewport range
  • Shareable ?link= URLs — share a URL that auto-loads the preview with your target site pre-encoded
  • Portrait / Landscape orientation toggle — swaps width and height for any device preset instantly
  • Custom W×H input — enter any arbitrary viewport dimensions for non-standard screen sizes
  • Zoom controls — 25/50/75/100% quick presets, Fit-to-window auto-scale, and + / − fine controls
  • Breakpoint ruler — highlights 375/768/1024/1280/1440px breakpoint markers along the frame edge
  • Canvas background options — Dots, Grid, Dark, Light for different review contexts
  • Viewport dimensions displayed below the preview frame for precise reference
  • X-Frame-Options block detection with clear error message and "Open in new tab" fallback link
  • 100% free — no sign-up, no extension needed, works in any modern browser

How to Use

Type or paste any publicly accessible website URL into the address bar at the top — include the full URL with the https:// prefix. Press Enter or click the Go button to load the site inside the preview frame at the currently selected device viewport size. The browser loads the target site inside an iframe constrained to the exact pixel dimensions of the selected device. Choose a different device from the presets dropdown to instantly resize the viewport — select Mobile S (320px) to test the smallest common mobile viewport, iPhone (390px) for modern iPhone sizes, Tablet Portrait (768×1024) for standard tablet, or any of the larger presets for laptop and desktop layout checks. Click the Orientation toggle button to flip between portrait and landscape mode — the width and height swap so you can test, for example, how a tablet layout responds when the device is rotated. For non-standard sizes, select Custom from the presets and type your own width and height values directly. Use the zoom controls to scale the preview if the device viewport is wider than your browser window: click 50% to see the full preview at half scale, or click Fit to automatically scale the preview to fill your available screen area. The page URL updates to include ?link= with the encoded target URL whenever you preview — copy that URL to share a pre-configured preview with any team member or client for instant feedback without any setup on their end.

Common Use Cases

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Responsive Development
Testing each responsive breakpoint by manually resizing the browser window is slow and imprecise. This tool lets you jump between exact device viewport widths instantly — from 320px mobile to 1920px desktop — and see the layout at each breakpoint without a browser extension or device lab. The breakpoint ruler highlights the standard CSS breakpoints so you can verify that your media queries fire at the right dimensions.
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Pre-Launch QA
Before a deployment, systematically check every important page at each device size using the presets to ensure nothing breaks, overflows, or renders incorrectly at any viewport. The orientation flip lets you verify both portrait and landscape modes for tablet viewports. Share a ?link= URL with your QA team so everyone tests the same site at the same device configuration without any setup.
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Client Presentations
Instead of explaining responsive design to non-technical clients, show them their site in the preview at each device size and switch between mobile, tablet, and desktop presets in seconds. Share a ?link= URL so the client can open the preview in their own browser and explore different device sizes independently after the meeting without installing anything.
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Cross-Device Bug Reports
When a user reports a layout issue on a specific device, reproduce it precisely by loading the URL at the reported device's viewport size. The custom W×H input lets you test at the exact reported dimensions even for uncommon or obscure screen sizes. Screenshot the issue at the exact viewport and include the dimensions in the bug report for precise reproduction steps that the development team can follow.
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Design Handoff Review
Use the tool during design handoff to verify that the implemented layout matches the design specifications at each breakpoint. Paste the staging URL, switch between the device sizes specified in the design file, and compare the rendered layout to the mockups. The zoom-to-fit option lets you see the full page layout at once for any device size without scrolling.
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Third-Party Site Monitoring
Check competitor sites, client sites maintained by other teams, or external tools your product integrates with across device sizes without installing anything. The ?link= shareable URLs make it easy to create a set of bookmarks for regularly checked URLs at specific device presets, turning this into a lightweight repeatable monitoring workflow for ongoing cross-device verification.

Frequently Asked Questions

Responsive Preview Tool loads any publicly accessible website inside an iframe at exact device viewport pixel dimensions, letting you see how the site responds at different screen sizes without resizing your browser window. You can switch between 10 device presets covering mobile, tablet, and desktop widths, flip orientation between portrait and landscape, use a custom size input for non-standard viewports, and zoom the preview to fit your screen. When you preview a URL the page URL updates to include a ?link= parameter, so you can share the exact preview configuration with teammates or clients.

When you enter a URL and click Preview, the tool appends a ?link= query parameter to its own page URL encoding your target site's address. Anyone who opens that URL will see the target site immediately loaded in the preview at the default device size. You can also manually construct shareable URLs in the format /responsive-preview-tool?link=https://yoursite.com to create permanent bookmarks or share links in Slack, email, or design review documents for your team.

The tool includes 10 device presets: Mobile S (320×568), Mobile M (375×667), Mobile L (428×926), Tablet Portrait (768×1024), Tablet Landscape (1024×768), iPad Pro Portrait (1024×1366), iPad Pro Landscape (1366×1024), Laptop (1280×800), Desktop (1440×900), and Wide 2K (1920×1080). A Custom option lets you enter any arbitrary width and height values for non-standard viewport sizes that fall outside the preset list.

Many websites set the X-Frame-Options: DENY or SAMEORIGIN HTTP header, or use Content-Security-Policy: frame-ancestors 'none' to block being embedded in iframes as a protection against clickjacking attacks. If the tool detects this block, it shows an error message with a direct link to open the page in a new tab for manual inspection. Major sites like Google, Facebook, and most banking sites use this iframe protection by design.

Yes. Click the Portrait/Landscape toggle button in the controls bar to swap the width and height dimensions of the currently selected device preset. For example, iPad Pro Portrait (1024×1366) becomes 1366×1024 in landscape mode. This lets you quickly test how your responsive layout responds to device rotation on tablet and large-phone viewports, which is important for apps that support both orientations.

Use the 25/50/75/100% quick preset buttons to scale the preview to a fraction of its actual size — useful when the target device (e.g. 1920px wide) is wider than your browser window. The Fit button auto-calculates the exact zoom percentage needed to fill your available screen area with the full device preview at the current viewport dimensions. Use + and − buttons for fine-grained zoom adjustment between the standard presets.

No. The tool only controls the CSS viewport width — it does not simulate touch events, devicePixelRatio, media features like hover: none, or pointer: coarse. For full hardware simulation including touch events, high-DPI rendering, and mobile-specific CSS media features, use Chrome DevTools' Device Emulation mode or test on actual hardware. This tool is best for quickly checking layout and content reflow across a range of viewport widths.

To preview localhost URLs, open this tool in the same browser where your local server is running and type your localhost URL (e.g. http://localhost:3000) into the address bar. The browser can load local addresses in iframes if both origins are localhost. However, since this tool is served from a different origin, some browsers may block the cross-origin iframe for security reasons. If blocked, use Chrome DevTools' built-in Responsive Design Mode for localhost development testing.