X-Frame-Options: This HTTP header controls whether a page can be displayed in an iframe. Values include DENY (never), SAMEORIGIN (same domain only), or ALLOW-FROM (specific domains).

Content Security Policy (CSP): The frame-ancestors directive specifies which domains can embed the page. More flexible than X-Frame-Options but requires modern browser support.

JavaScript Detection: Some sites use JavaScript to detect if they're being framed and break out of the iframe (framebusting). This is often used by social media and banking sites.

Why This Tool Exists: Many websites block iframe embedding for security reasons. This tool lets you test any URL by attempting to load it in an iframe. The most reliable way to know if a site allows embedding is to simply look at the result - if you see the actual website, it works. If you see an error page, it's blocked.

Common Blocking Methods: Sites use X-Frame-Options headers, CSP frame-ancestors directives, or JavaScript framebusting to prevent embedding. When blocked, browsers typically show an error page inside the iframe instead of the actual content.