What is Iframe Tester?
The Iframe Tester loads any URL inside an <iframe> so you can see how a page behaves when embedded and how it responds at different screen sizes. Switch between mobile, tablet, laptop and desktop presets or set a custom width and height, rotate the viewport, and scale the frame to fit. It also reveals when a site refuses to be embedded — if the frame stays blank, the page is protected by X-Frame-Options or a Content-Security-Policy frame-ancestors rule.
How Iframe Tester works
How to test a page in an iframe
- Enter a URL and press Load.
- Pick a device preset (Mobile, Tablet, Laptop, Desktop) or type a custom width and height, and use Rotate to swap them.
- Watch the page render in the frame; turn on Scale to fit so large viewports fit your screen.
Why some pages stay blank
Many sites send an X-Frame-Options: DENY/SAMEORIGIN header or a Content-Security-Policy: frame-ancestors rule that stops them being shown in an iframe on another domain — Google, YouTube, banks and many apps do this for security. If the frame is blank, that site cannot be embedded. Everything runs locally in your browser.
Common uses
- Preview how your site looks embedded in an iframe
- Test a page responsively at mobile, tablet and desktop sizes
- Check whether a URL allows being embedded (X-Frame-Options / CSP)
- Debug widgets, embeds and oEmbed previews
- Demo a responsive layout at exact viewport sizes