Frequently asked questions
Why is the preview blank for some sites?
Many big websites (Twitter/X, Facebook, NYTimes, GitHub, Instagram, banks) explicitly refuse to be embedded in any iframe. They send a header called X-Frame-Options: DENY or Content-Security-Policy: frame-ancestors 'none'. This is a security feature against clickjacking — it has nothing to do with our tool. Browsers respect it and show a blank frame. Workaround: open Chrome/Firefox DevTools (F12 → Toggle Device Toolbar) directly on the site itself, or test a site you control.
Is my URL really not uploaded?
Correct. The URL you enter is read by JavaScript in your browser and put directly into an iframe. The iframe then connects to that URL from your computer — not from our server. Verify by pressing F12 → Network tab → typing a URL → clicking Test. You will see exactly one request: from your browser to the URL you entered. No request goes to our domain with your URL in it.
Does this really show how the site looks on a real phone?
For 95% of cases, yes. The iframe is sized exactly to the device's CSS viewport (e.g. 390×844 for iPhone 13), and the page renders against that width. CSS media queries fire as they would on the real device. What we can't simulate: touch-only interactions (hover effects look slightly different), real device pixel ratio in some cases, and browser-specific quirks (Safari on iOS sometimes renders differently from Chrome on iOS). For the final QA pass, use real hardware or a service like BrowserStack — but for 90% of "does my responsive layout work?" checks, an iframe is enough and it's free.
Can I test sites that need login?
Yes — but you'll need to log in inside the iframe each time. Cookies are not shared between the iframe and your normal browser tabs (each origin is isolated). Some sites also block iframe loading entirely (see the first question), in which case login isn't possible and you need a different approach (DevTools on the live site, or a tool like BrowserStack).
Why a Pro mode?
Easy mode shows you one device at a time — perfect for "how does this look on a phone?". Pro mode lets you compare two, three, or four viewports side-by-side with synced scrolling, custom widths/heights, breakpoint rulers, and shareable layouts. Designers and developers usually want Pro mode after the first 30 seconds.
Does it work on my phone?
It works, but it's awkward — you'd be looking at a tiny iframe of how a different phone would render the page on the phone you're already using. Recommended: use a laptop or desktop. If you only have a phone, the easy-mode view at "Phone" size is roughly your own screen anyway.
Can I save a layout to share with a colleague?
Yes, in Pro mode. Click "Share layout" and we generate a URL that contains your tested URL plus the device list as a query string. Send it to anyone — when they open it, they see exactly the same setup. The URL is local to this page; no server is contacted to create or resolve it.
What devices does it know about?
All the modern iPhones (SE through 15 Pro Max), most modern Androids (Galaxy S22-S24, Pixel 7-8), iPads (Mini 6 through Pro 12.9"), Galaxy Tabs, Surface Pro, and standard laptop/desktop sizes from 1280×800 to 4K UHD. In Pro mode you can also enter any custom width and height. The complete list is in the device dropdown when you switch to Pro mode.
What's the catch?
There isn't one. The tool is provided free as part of Midgard MUD's small toolkit (alongside our EXIF metadata remover at /tools/exif/). No ads, no sign-up, no data collection. If you find it useful, drop us a coffee — but you don't have to.