Responsive Website Tester
Preview any website on multiple screen sizes simultaneously. Faster than browser DevTools.
📖 Complete Guide to Responsive Website Testing
In today's multi-device world, your website must work flawlessly across smartphones, tablets, laptops, and desktop monitors. With mobile devices accounting for over 55% of global web traffic and Google using mobile-first indexing, responsive design isn't optional—it's essential. Our Responsive Website Tester lets you preview any website across multiple screen sizes simultaneously, dramatically faster than manually resizing your browser.
Traditional responsive testing involves repeatedly resizing your browser window or cycling through device presets in browser DevTools. This process is slow, disruptive to your workflow, and makes it difficult to compare how a page looks across multiple sizes at once. Our tool loads your website in multiple viewports simultaneously, giving you an instant overview of responsiveness without the back-and-forth.
📱 Understanding Device Presets
Our tool includes four carefully chosen device presets that represent the major breakpoints in responsive design:
| Device | Dimensions | Represents | Common Breakpoint |
|---|---|---|---|
| 📱 Mobile | 375 × 667 | iPhone SE, iPhone 8, similar Android phones | < 576px (Bootstrap XS) |
| 📱 Tablet | 768 × 1024 | iPad (portrait), Android tablets | 576px - 992px (Bootstrap SM/MD) |
| 💻 Laptop | 1366 × 768 | Most common laptop resolution worldwide | 992px - 1200px (Bootstrap LG) |
| 🖥️ Desktop | 1920 × 1080 | Full HD monitors, most common desktop resolution | > 1200px (Bootstrap XL) |
🎛️ View Mode Options
Three layout options let you customize how the device previews are displayed:
- Grid View: Shows all enabled devices in a responsive grid layout. Best for getting a quick overview of how your site looks across all screen sizes simultaneously. The default and most commonly used view.
- Stack View: Arranges devices vertically in a single column. Useful when you want to scroll through devices one by one, or when working on a narrow screen where grid layout is cramped.
- Focus View: Shows one device at a time at larger scale with navigation buttons to switch between devices. Best for detailed examination of specific viewport behavior.
🔧 Device Controls
Each device frame includes controls for individual manipulation:
| Control | Function | Use Case |
|---|---|---|
| 🔄 Rotate | Swaps width and height dimensions | Test portrait vs landscape orientation |
| ↻ Refresh | Reloads the page in that specific viewport | Test loading states, reset after interaction |
| ↗ Open | Opens the URL in a new browser tab | Use when iframe embedding is blocked |
➕ Custom Device Sizes
The Custom Device feature lets you test any specific dimensions you need. This is invaluable for:
- Specific Device Testing: Test exact dimensions of devices your audience uses (check your analytics for popular resolutions)
- Breakpoint Debugging: Test dimensions just above and below your CSS breakpoints to catch edge cases
- Unusual Aspect Ratios: Test ultra-wide monitors, folding phones, or embedded displays
- Client Requirements: When a client specifies particular device requirements, test those exact sizes
⚠️ Important: Some websites block iframe embedding using security headers (X-Frame-Options or Content-Security-Policy). This is a security feature, not a bug. Major sites like Facebook, Twitter, banking sites, and many e-commerce platforms block embedding. If a site won't load, use the "Open in new tab" button to view it directly, or test in browser DevTools instead.
🚀 Why Use This Over Browser DevTools?
Browser DevTools are excellent for debugging, but our tool excels at visual comparison:
- Simultaneous Comparison: See all viewports at once instead of switching between them one at a time
- Faster Workflow: No need to repeatedly resize, screenshot, or toggle device emulation
- Client Presentations: Show clients their site across devices in a single view
- Design Review: Designers can quickly assess responsive behavior without technical knowledge
- Team Collaboration: Share URLs with query parameters to show specific configurations
For detailed CSS debugging, DOM inspection, or network analysis, DevTools remains the better choice. Our tool complements DevTools for the visual comparison aspects of responsive testing.