See your website on every device — instantly.
Paste any URL and preview it on iPhone, Galaxy, Pixel, iPad, MacBook & desktop side by side. Spot issues, copy the fix. No signup, no limits.
✅ Visual issue checklist
Click once = passes, twice = has issue. Every issue links to its copy-paste fix and goes into your report.
Shortcuts: / URL · R rotate · F fullscreen · +/− zoom · ? help
Check your mobile app too — not just websites
Frame your app screenshots on real devices with notch & safe-area guides, run your APK/IPA live on several phones, or preview Flutter / React Native web builds.
Found a problem? Here's the fix.
The 18 most common responsive bugs on websites and mobile apps — how to spot them, and copy-paste code to fix them (CSS, Flutter, React Native, Android).
What's my screen size?
Your live viewport, screen resolution and pixel ratio — plus a one-click bookmarklet to test any page you're on.
Your browser viewport (CSS pixels) · —
Responsivly bookmarklet
Drag this button to your bookmarks bar. On any website, click it to open that page in Responsivly instantly.
📱 Test in Responsivly- Show your bookmarks bar (Ctrl+Shift+B).
- Drag the purple button onto it.
- Open any site and click the bookmark.
On mobile? and save it as a bookmark URL.
Responsive testing in three steps
Over 60% of web traffic is mobile. If your layout breaks on small screens, visitors leave and Google ranks you lower.
Paste your URL
Any public website — or your localhost exposed via ngrok / Cloudflare Tunnel.
Pick devices & spot issues
Choose any of 56 viewports, compare A vs B, then tick the visual checklist.
Copy the fix & share
Grab copy-paste CSS for each issue, then send the report or share link to your developer.
Everything you need to ship a perfect responsive site
App checker NEW
Frame app screenshots with safe-area guides, check store sizes, run APK/IPA live.
Multi-device preview
Phones, tablets & desktops side by side — spot breakpoint issues at a glance.
56 real presets
iPhone 17 Pro Max, Galaxy S24 Ultra, Z Fold 5, Pixel 9 Pro XL, Infinix, iPad Pro, MacBook & more.
A vs B compare NEW
Your site vs a competitor — or staging vs production — on the same device.
Issues & Fixes NEW
18 web & app bugs with how-to-spot tips and CSS / Flutter / React Native fixes.
Visual checklist NEW
Mark pass / fail while testing — failed items link to fixes and land in your report.
Width slider & breakpoints
Drag from 240px to 1920px or jump to common CSS breakpoints in one tap.
Zoom & auto-fit
Scale frames 20–100% or auto-fit everything into your screen.
Portrait & landscape
Rotate every device in one click — or press R.
Favourites & history
Star your go-to devices; recent URLs stay in your browser.
QR real-device test
Scan and verify on your physical phone in seconds.
Share links & reports
URL, devices, mode & orientation saved in the link. Download a .txt report.
56 device screen sizes (CSS viewports)
Every popular phone, tablet and desktop size in one place. Open a device for its full specs and media query, or test your site on it in one click.
More features. Zero limits.
| Feature | Responsivly | Typical checkers |
|---|---|---|
| Price | Free forever | Free tier + paid plans |
| Test limit | Unlimited | ~20 tests, then signup |
| Signup required | Never | For more tests |
| Device presets | 56 + custom | ~50 |
| A vs B comparison | ✓ | ✕ |
| Issue fixes with code | ✓ 18 fixes | ✕ |
| Width slider & breakpoints | ✓ | ✕ |
| Mobile app checks | ✓ Screenshots + APK/IPA | ✕ |
| QR real-device test | ✓ | ✕ |
| Works on small screens | ✓ | Needs 1400px+ screen |
Frequently asked questions
We fix them. Fast.
AKCLNT builds lightning-fast, fully responsive websites, AI chatbots & automation for startups and businesses.
Get your site fixed →