iframetest.dev

iframetest.dev is a free browser tool for testing whether a website can be embedded in an iframe. You enter a public URL and it loads a live preview at desktop, tablet or mobile size. It also fetches the page's response headers and redirects separately, so you can see whether X-Frame-Options or a Content-Security-Policy frame-ancestors directive is blocking the embed.

The tool includes an embed code generator. You set width, height, an accessible title, responsive width, lazy loading, fullscreen and sandbox permissions, then copy the resulting HTML. The site also has standalone generator and header checker pages, plus guides on "refused to connect" errors, X-Frame-Options versus CSP, and responsive iframes.

The FAQ is clear about the limits. The tool checks a public, unauthenticated response, which may differ from what your browser receives. It cannot read cookies or console errors from third-party sites.