Free Responsive Tester Online

Test how your website looks on different screen sizes and devices. Preview desktop, tablet, and mobile views.

Last updated May 8, 2026

Width

Height

Viewport: 390 x 844

Enter a URL above to test responsiveness

Preview will appear here

Note: Some websites may block iframe embedding (X-Frame-Options). If a site doesn't load, try opening it directly in a new tab with the external link button.

Mobile traffic now exceeds desktop on most websites globally — over 60% on average — and Google's mobile-first indexing means your site is judged primarily on how it looks and performs on a phone. But every developer knows the agony of designing a beautiful desktop layout only to discover on launch day that it breaks horribly on iPhone, looks weird on iPad, and overflows on Android. Our free online responsive tester lets you preview any live website at every common device size in seconds — no real phones to juggle, no DevTools to wrangle, no setup. Type the URL, pick a device preset, and the site renders at exact viewport dimensions inside an iframe. Switch between iPhone (multiple models, including the latest Pro Max with notch dimensions), iPad (mini, regular, Pro), Android phones (Pixel, Galaxy, OnePlus), Android tablets, and various desktop sizes (laptop 1366×768, MacBook 1440×900, full HD 1920×1080, ultrawide 2560×1080). Toggle between portrait and landscape to catch issues in both orientations. Or enter custom width and height for niche cases (smart TVs, kiosk displays, small webview windows). Common workflows people run it for: checking your own site looks good on mobile before deploying a new release, debugging a CSS layout issue that only appears at certain breakpoints, comparing how your site looks against a competitor at the same screen size, demonstrating a design issue to a remote teammate or client without screen-sharing, and quickly previewing how a third-party landing page renders on devices you do not own. **Important boundary:** this is a viewport simulator, not a full device emulator. It accurately reproduces screen dimensions and triggers the same CSS media queries a real device would, but it does not simulate device-specific quirks (iOS Safari's notch handling, Android Chrome's scrollbar behaviour, true touch event handling, or device-specific font rendering). For high-fidelity testing, real devices, BrowserStack, or LambdaTest are the right tools. For 90% of "does my responsive design break?" questions during everyday development, this simulator is faster and more convenient. **Another caveat:** some websites set HTTP headers (X-Frame-Options: DENY or Content-Security-Policy with frame-ancestors: 'none') that block iframe embedding for security. Major sites like Google, Facebook, banking portals, and most social media block themselves from iframes — they will fail to load in the tester. Your own sites and most public marketing/blog sites work fine. Pair this with our [Mobile-Friendly Test](/tools/mobile-friendly-test) for Google's official mobile-friendliness audit, [Website Speed Test](/tools/website-speed-test) for performance metrics, [Live Code Editor](/tools/live-code-editor) for testing your own code's responsive behaviour, and [SEO Title Analyzer](/tools/seo-title-analyzer) for SEO optimization.

How to Use Responsive Tester

Enter URL

Type or paste the website URL you want to test for responsive design. The tool validates the URL and loads it in the preview iframe.

Choose Device

Select from preset device sizes (iPhone 15, iPad Pro, Pixel 8, Galaxy, MacBook, Full HD, etc.) or enter custom dimensions for niche viewports. Switch between portrait and landscape with one click.

Preview & Test

View the website at the selected viewport size. Scroll inside the preview to test long-page responsive behaviour. Switch between devices to compare layouts side-by-side mentally.

Features

Preset Devices

Test on popular device sizes including iPhone 15, iPhone 15 Pro Max, iPad mini/regular/Pro, Pixel 8, Galaxy S24, OnePlus, Android tablets, MacBook, and various desktop resolutions.

Custom Dimensions

Enter any custom width and height to test at specific resolutions — useful for smart TV screens, kiosk displays, embedded webviews, or testing exact CSS breakpoint values.

Live Preview

The website renders in real-time at the selected viewport size. CSS media queries trigger correctly because the iframe receives the exact pixel dimensions a real device would have.

Portrait/Landscape

Toggle between portrait and landscape orientations to catch issues that only appear in one mode — landscape is often forgotten in CSS testing but matters for mobile users.

No Installation

Browser-based tool — no app to install, no extension to add, no DevTools to learn. Faster than firing up Chrome DevTools device mode for casual checks.

Public URL Testing

Test any publicly accessible URL — your own site, a competitor, a client preview link, a landing page from an email campaign. Just paste the URL.

Benefits of Using Responsive Tester

Completely Free

Use Responsive Tester without any cost, limits, or hidden fees. No premium plans needed.

No Installation

Works directly in your browser. No software downloads or plugins required.

100% Private

Your files and data are processed locally. Nothing is uploaded to external servers.

Works Everywhere

Compatible with Chrome, Firefox, Safari, Edge on desktop, tablet, and mobile.

No Sign-Up

Start using the tool immediately. No account creation or email verification.

Always Available

Access this tool 24/7 from anywhere in the world, on any device.

Frequently Asked Questions

Most websites yes, but some sites block iframe embedding for security via HTTP headers (X-Frame-Options: DENY or Content-Security-Policy). Major sites that block: Google, Facebook, Twitter/X, Instagram, LinkedIn, banking portals, payment gateways, most enterprise SaaS dashboards. Sites that allow embedding: your own sites, most marketing pages, blogs, news sites, e-commerce, documentation pages, and most public content. If a site fails to load, it has likely blocked iframe embedding deliberately.

Chrome DevTools device mode (Cmd/Ctrl+Shift+M) is the gold standard for serious responsive debugging — it includes touch event simulation, network throttling, device pixel ratio simulation, and accurate user-agent strings. Our tester is the lighter alternative: faster to load, no need to know DevTools, easier to switch between devices for comparison, and works from any URL bar. Use DevTools for deep development debugging; use this for quick visual checks and demos.

No, not fully. The tester accurately reproduces viewport dimensions (so CSS media queries trigger correctly) but does not simulate device-specific quirks: iOS Safari's notch and home-indicator safe areas, Android Chrome's scrollbar behaviour differences, real touch events versus mouse hover, device pixel ratio rendering, mobile-only font rendering quirks, or carrier-specific HTTP behaviour. For these high-fidelity scenarios, use real devices, BrowserStack, or LambdaTest. For everyday "does my CSS break at this width?" questions, viewport simulation is sufficient.

Cover the breakpoints that matter for your audience. Common essentials: 375×667 (iPhone SE / smallest modern iPhone), 390×844 (iPhone 14/15), 412×915 (Pixel/Galaxy), 768×1024 (iPad portrait), 1024×768 (iPad landscape), 1366×768 (most common laptop), 1440×900 (MacBook), 1920×1080 (most common desktop). For your specific site, check Google Analytics for the actual device dimensions your traffic uses and prioritise those. Test landscape too — it often breaks layouts that work fine in portrait.

Several reasons. (1) The tester does not change user-agent string, so the server may serve different content for "real iPhone" vs the simulator (some sites have UA-based redirects). (2) Real devices have device-pixel-ratio of 2× or 3× — fonts and small graphics may render slightly differently. (3) Real iOS Safari has different scroll bounce, address bar collapse behaviour, and form input rendering. For most layout testing, the differences are cosmetic; for production verification, real devices or BrowserStack remain authoritative.

For Google's mobile-friendliness assessment specifically, use the [Mobile-Friendly Test](/tools/mobile-friendly-test) tool which runs Google's actual evaluation. The responsive tester here helps you visually check that your site looks good at mobile dimensions before submitting to the SEO audit. Both tools are useful: the responsive tester for visual debugging, the mobile-friendly test for the formal Google evaluation that affects search rankings.

Yes, completely free with no limits on the number of websites you can test, sessions per day, or devices to switch between. No registration. The tool runs in your browser — your test sessions are entirely local.

No, because localhost URLs are only accessible from your own device — the iframe in our tool runs in your browser but is loaded from flexypdf.com's domain, so it cannot reach `localhost:3000`. For testing local development, use Chrome DevTools device mode or set up a tunnel like ngrok to expose your localhost as a public URL, then test that URL here.

Complete Your Developer Tools Workflow

These free tools work seamlessly with Responsive Tester to handle every step of your workflow.

Mobile-Friendly Test →

Google official mobile-friendliness audit

Website Speed Test →

Test page load performance

Live Code Editor →

Test your own code's responsiveness

SEO Title Analyzer →

Optimise page SEO

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