What you get
- The full report on every device you choose — screenshots with each problem highlighted, a score, and plain-English fixes for small text, low contrast, tiny tap targets, sideways scrolling, sticky bars, dark mode, large text and the mobile menu.
- A phone window — open any page in a window with the exact screen, pixel density, touch input and user agent of the device, then tap, scroll and type. Switch devices, rotate and toggle dark mode without losing your place.
- Your pages, your network — test
localhost, staging servers, intranets and signed-in pages that our servers can't reach. - Reports that stay with you — kept in your browser, printable to PDF, or saved as one HTML file to send to a client or developer.
How to use it
- Click the MobileCheck button in the toolbar on the page you want to test (or press Alt+Shift+M).
- Pick devices and extra checks, then Run test. A small test window opens and goes through the devices one by one.
- Read the report, open any device to see the problems on its screenshot, or open the page in a phone window to try it by hand.
Extension or website?
| Website | Extension | |
|---|---|---|
| Price | Free | Free |
| Where it runs | On our server, shared by everyone | On your computer |
| iPhone engine | WebKit, Safari's engine | Chrome's engine, emulating the iPhone |
| Checks | No daily limit, up to all 51 devices; one line for everyone, so you may wait a few minutes | No waiting, up to all 51 devices |
| localhost, staging, logged-in pages | No | Yes |
| Phone window (tap around by hand) | — | Yes, no time limit |
| Report | Private link for 24 hours | Kept in your browser; HTML file or PDF |
Using both is a good routine: the extension while you build, the website's Safari engine before you ship. See why Chrome's iPhone mode isn't Safari.
Permissions, explained
- Debugger — to emulate a device in the test window (screen size, pixel density, touch, user agent, dark mode) and take screenshots. Chrome describes this permission as access to the page debugger backend and to your data on websites; the extension uses it only on the windows it opens itself.
- Storage — to keep your reports and screenshots in your browser.
- Context menus and active tab — for “Test this page on phones” in the right-click menu and to read the address of the page you started from.
- mobilefriendlycheck.com — so this website can hand a test over to the extension when you choose “Run in my browser”.
Details are in the extension privacy policy.
Frequently asked questions
How is the extension different from the website?
Both are free. The website tests your page on our server, with WebKit, Safari's engine, for iPhones; because that server is shared by everyone, checks wait in one line. The extension runs the same checks on your own computer, so there is no waiting: all 51 devices at once, the interactive phone window, pages behind your login, localhost and staging sites. iPhones are emulated with Chrome's engine there, so use the website when Safari's rendering matters.
Why does Chrome say the extension "started debugging this browser"?
The extension emulates phones through Chrome's DevTools protocol, the same interface Chrome's own device mode uses. Chrome shows that notice whenever an extension uses it. It appears only while a test or a phone window is running and disappears when it ends.
Does it send my pages or reports anywhere?
No. Pages load in your browser, and screenshots and reports are saved in your browser's storage. The extension has no analytics and makes no requests to our servers.
Which browsers does it work in?
Google Chrome, Microsoft Edge, Brave, Opera, Vivaldi and other Chromium-based browsers, version 125 or newer. Firefox and Safari don't offer the device-emulation interface the extension needs.
Can it test pages that need a login?
Yes. Pages open with your browser's cookies, so you see them as you do when you're signed in. That also means a test can accept a cookie banner on your behalf, as you would.