Responsive checker
Enter a page address and see it on a phone, a tablet and a desktop screen side by side, at the sizes real devices use.
How to use the responsive checker
- Enter the addressAny public page, live or on a staging link.
- Pick the devicesChoose the phone, tablet and desktop sizes your visitors use.
- Collect commentsSend it for review, with phone, tablet and desktop notes kept apart.
What it checks
Why check every screen size
More than half of web visits come from phones, and the phone version of a page is often the one nobody looked at closely. A layout that is perfect on a 27-inch monitor can bury the main button below a photo on a phone, or squeeze a pricing table until it is unreadable on a tablet.
Desktop browsers can imitate phones in their developer tools, but most clients and marketers never open them. Seeing the three sizes side by side makes problems obvious in seconds.
What to look for
- The first screen on a phone. Does it say what you sell and show the main button without scrolling?
- Text size. Body text should be readable without zooming, and lines on desktop shouldn't run the full width of a wide screen.
- Tap targets. Buttons and links need room around them so a thumb hits the right one.
- Images. Check photos aren't cropped in a way that cuts off the subject on narrow screens.
- Tables and forms. Wide tables should scroll sideways on a phone, and form fields should fit the screen.
- Menus. Open the menu at each size and check every item is reachable.
When a site won't show in the checker
Some sites tell browsers not to display them inside another page. It is a security setting, common on banks, large stores and sites like GitHub. When that happens we tell you, and you can open the page in HTMLAnnotate instead, which shows it at desktop, tablet and phone sizes in its own review view.
Pages that only work over http:// also can't be shown inside a secure https:// page. Most sites have an https:// address; try that one.
From checking to feedback
Spotting a layout problem is half the job; agreeing what to change is the other half. Send the page as a review link and reviewers can switch between desktop, tablet and phone and comment on each. Comments left on the phone view stay on the phone view, so a note about the mobile menu never gets mixed up with a desktop one.
Related guides
Questions
Is the responsive checker free?
Yes. There is no signup, and you can check as many pages as you like.
Which device sizes does it use?
Real screen sizes in CSS pixels: phones from the iPhone SE (375 by 667) to the iPhone 16 Pro Max (440 by 956), tablets from the iPad mini to the iPad Pro 13 inch, and laptop and desktop sizes.
Why does a site not load in the checker?
Some sites forbid being shown inside another page, as a security setting. We detect this and offer to open the page in HTMLAnnotate, which can show it at every size.
Is this the same as testing on a real phone?
It shows the same layout a phone would at that width, which catches most problems. Fonts and some browser features can differ slightly on the real device, so test the final version on a phone in your hand too.
Can I check a staging site?
Yes, if it opens without a sign-in and allows itself to be shown in a frame.
Can my client leave comments on the phone version?
Yes. Send it as an HTMLAnnotate review link. Reviewers switch to the phone view and comment there, and those comments stay with the phone view.