Viewpo
Free responsive design checker with real browser rendering
Most responsive checkers use iframes that break on modern sites. Viewpo uses real Chromium rendering and gives you an A-F grade with specific issues to fix.
What to look for in a responsive design checker
Key criteria for choosing the right tool — and how Viewpo stacks up.
Real browser rendering
Iframe-based tools fail when sites block embedding. A real browser renders every site accurately, including those with strict security headers.
Viewpo uses Chromium on Cloudflare's global network — no iframes, no failures.
Automated issue detection
Seeing your site at different sizes isn't enough. You need to know what's actually broken — overflow, touch targets, contrast, and more.
Viewpo runs 5+ automated checks and explains every issue in plain English.
Shareable results
A responsive check is only useful if you can share it with your team, your client, or yourself across sessions.
Every Viewpo audit generates a unique, shareable URL with OG preview cards.
No install required
The best responsive checker should work instantly — paste a URL and go, without downloading desktop software.
Viewpo is entirely web-based. Paste a URL, get results in seconds.
Why most responsive design checkers don't work
The majority of free responsive checkers use iframes to display your site at different sizes. The problem? Most modern websites set X-Frame-Options or Content-Security-Policy headers that block iframe embedding. You paste your URL, and get a blank page or "Refused to display" error. These tools were built for a web that no longer exists.
What Viewpo does differently
Viewpo uses a real Chromium browser running on Cloudflare's global network to render your site. It takes actual screenshots at phone (375px), tablet (820px), laptop (1440px), and desktop (1920px) sizes. Then it runs automated checks for overflow, touch targets, contrast, and accessibility — and gives you an A-F grade with plain-language explanations of every issue.
Frequently Asked Questions
Common questions about choosing a responsive design checker.
A responsive design checker is a tool that shows you how your website looks at different screen sizes — typically phone, tablet, and desktop. Better tools go further by detecting specific responsive design issues like content overflow, touch target sizing, and contrast problems.
Try the responsive design checker that grades your site
Paste any URL and get real browser screenshots at multiple viewports with an A-F responsive design grade. Free, no install.
Free during beta. Plans from $19/mo at launch — early supporters get a lifetime discount.